Embolic protection devices

ABSTRACT

An embolic protection device for use in a blood vessel when an interventional procedure is being performed in a stenosed or occluded region to capture any embolic material which may be created and released into the bloodstream during the procedure. The device includes a filtering assembly having a self-expanding strut assembly and a filter element attached thereto. In one embodiment, the filtering assembly is attached to the distal end of a guide wire and is deployed within the patient&#39;s vasculature as the guide wire is manipulated into the area of treatment. A restraining sheath placed over the filtering assembly in a coaxial arrangement maintains the filtering assembly in its collapsed position until it is ready to be deployed by the physician. Thereafter, the sheath can be retracted to expose the filtering assembly which will then self-expand within the patient&#39;s vasculature. Interventional devices can be delivered over the guide wire and any embolic debris created during the interventional procedure and released into the blood stream will enter the filtering assembly and be captured therein. Other embodiments include filtering assemblies attached to an outer tubular member and inner shaft member which apply axial force to the distal ends of the assembly to either expand or contract the struts as needed.

This application is a continuation-in-part of application Ser. No.9/490,319 filed Jan. 24, 2000, which is a continuation-in-part ofapplication Ser. No. 09/476,159 filed Dec. 30, 1999, which are assignedto the same Assignee as the present application.

The present invention relates generally to filtering devices and systemswhich can be used when an interventional procedure is being performed ina stenosed or occluded region of a blood vessel to capture embolicmaterial that may be created and released into the bloodstream duringthe procedure. The embolic filtering devices and systems of the presentinvention are particularly useful when performing balloon angioplasty,stenting procedures, laser angioplasty or atherectomy in criticalvessels, particularly in vessels such as the carotid arteries, where therelease of embolic debris into the bloodstream can occlude the flow ofoxygenated blood to the brain or other vital organs, which can causedevastating consequences to the patient. While the embolic protectiondevices and systems of the present invention are particularly useful incarotid procedures, the inventions can be used in conjunction with anyvascular interventional procedure in which there is an embolic risk.

A variety of non-surgical interventional procedures have been developedover the years for opening stenosed or occluded blood vessels in apatient caused by the build up of plaque or other substances on the wallof the blood vessel. Such procedures usually involve the percutaneousintroduction of the interventional device into the lumen of the artery,usually through a catheter. In typical carotid PTA procedures, a guidingcatheter or sheath is percutaneously introduced into the cardiovascularsystem of a patient through the femoral artery and advanced through thevasculature until the distal end of the guiding catheter is in thecommon carotid artery. A guide wire and a dilatation catheter having aballoon on the distal end are introduced through the guiding catheterwith the guide wire sliding within the dilatation catheter. The guidewire is first advanced out of the guiding catheter into the patient'scarotid vasculature and is directed across the arterial lesion. Thedilatation catheter is subsequently advanced over the previouslyadvanced guide wire until the dilatation balloon is properly positionedacross the arterial lesion. Once in position across the lesion, theexpandable balloon is inflated to a predetermined size with a radiopaqueliquid at relatively high pressures to radially compress theatherosclerotic plaque of the lesion against the inside of the arterywall and thereby dilate the lumen of the artery. The balloon is thendeflated to a small profile so that the dilatation catheter can bewithdrawn from the patient's vasculature and the blood flow resumedthrough the dilated artery. As should be appreciated by those skilled inthe art, while the above-described procedure is typical, it is not theonly method used in angioplasty.

Another procedure is laser angioplasty which utilizes a laser to ablatethe stenosis by super heating and vaporizing the deposited plaque.Atherectomy is yet another method of treating a stenosed blood vessel inwhich cutting blades are rotated to shave the deposited plaque from thearterial wall. A vacuum catheter is usually used to capture the shavedplaque or thrombus from the blood stream during this procedure.

In the procedures of the kind referenced above, abrupt reclosure mayoccur or restenosis of the artery may develop over time, which mayrequire another angioplasty procedure, a surgical bypass operation, orsome other method of repairing or strengthening the area. To reduce thelikelihood of the occurrence of abrupt reclosure and to strengthen thearea, a physician can implant an intravascular prosthesis formaintaining vascular patency, commonly known as a stent, inside theartery across the lesion. The stent is crimped tightly onto the balloonportion of the catheter and transported in its delivery diameter throughthe patient's vasculature. At the deployment site, the stent is expandedto a larger diameter, often by inflating the balloon portion of thecatheter.

Prior art stents typically fall into two general categories ofconstruction. The first type of stent is expandable upon application ofa controlled force, as described above, through the inflation of theballoon portion of a dilatation catheter which, upon inflation of theballoon or other expansion means, expands the compressed stent to alarger diameter to be left in place within the artery at the targetsite. The second type of stent is a self-expanding stent formed from,for example, shape memory metals or super-elastic nickel-titanum (NiTi)alloys, which will automatically expand from a collapsed state when thestent is advanced out of the distal end of the delivery catheter intothe body lumen. Such stents manufactured from expandable heat sensitivematerials allow for phase transformations of the material to occur,resulting in the expansion and contraction of the stent.

The above non-surgical interventional procedures, when successful, avoidthe necessity of major surgical operations. However, there is one commonproblem which can become associated with all of these non-surgicalprocedures, namely, the potential release of embolic debris into thebloodstream that can occlude distal vasculature and cause significanthealth problems to the patient. For example, during deployment of astent, it is possible that the metal struts of the stent can cut intothe stenosis and shear off pieces of plaque which become embolic debristhat can travel downstream and lodge somewhere in the patient's vascularsystem. Pieces of plaque material can sometimes dislodge from thestenosis during a balloon angioplasty procedure and become released intothe bloodstream. Additionally, while complete vaporization of plaque isthe intended goal during a laser angioplasty procedure, quite oftenparticles are not fully vaporized and thus enter the bloodstream.Likewise, not all of the emboli created during an atherectomy proceduremay be drawn into the vacuum catheter and, as a result, enter thebloodstream as well.

When any of the above-described procedures are performed in the carotidor arteries, the release of emboli into the circulatory system can beextremely dangerous and sometimes fatal to the patient. Debris that iscarried by the bloodstream to distal vessels of the brain can causethese cerebral vessels to occlude, resulting in a stroke, and in somecases, death. Therefore, although cerebral percutaneous transluminalangioplasty has been performed in the past, the number of proceduresperformed has been limited due to the justifiable fear of causing anembolic stroke should embolic debris enter the bloodstream and blockvital downstream blood passages.

Medical devices have been developed to attempt to deal with the problemcreated when debris or fragments enter the circulatory system followingvessel treatment utilizing any one of the above-identified procedures.One approach which has been attempted is the cutting of any debris intominute sizes which pose little chance of becoming occluded in majorvessels within the patient's vasculature. However, it is often difficultto control the size of the fragments which are formed, and the potentialrisk of vessel occlusion still exists, making such a procedure in thecarotid arteries a high-risk proposition.

Other techniques which have been developed to address the problem ofremoving embolic debris include the use of catheters with a vacuumsource which provides temporary suction to remove embolic debris fromthe bloodstream. However, as mentioned above, there have beencomplications with such systems since the vacuum catheter may not alwaysremove all of the embolic material from the bloodstream, and a powerfulsuction could cause problems to the patient's vasculature. Othertechniques which have had some limited success include the placement ofa filter or trap downstream from the treatment site to capture embolicdebris before it reaches the smaller blood vessels downstream. However,there have been problems associated with filtering systems, particularlyduring the expansion and collapsing of the filter within the bodyvessel. If the filtering device does not have a suitable mechanism forclosing the filter, there is a possibility that trapped embolic debriscan backflow through the inlet opening of the filter and enter theblood-stream as the filtering system is being collapsed and removed fromthe patient. In such a case, the act of collapsing the filter device mayactually squeeze trapped embolic material through the opening of thefilter and into the bloodstream.

Many of the prior art filters which can be expanded within a bloodvessel are attached to the distal end of a guide wire or guide wire-liketubing which allows the filtering device to be placed in the patient'svasculature when the guide wire is manipulated in place. Once the guidewire is in proper position in the vasculature, the embolic filter can bedeployed within the vessel to capture embolic debris. The guide wire canthen be used by the physician to deliver interventional devices, such asa balloon angioplasty dilatation catheter or a stent, into the area oftreatment. When a combination of embolic filter and guide wire isutilized, the proximal end of a guide wire can be rotated by thephysician, usually unintentionally, when the interventional device isbeing delivered over the guide wire in an over-the-wire fashion. If theembolic filter is rigidly affixed to the distal end of the guide wire,and the proximal end of the guide wire is twisted or rotated, thatrotation will be translated along the length of the guide wire to theembolic filter, which can cause the filter to rotate or move within thevessel and possibly cause trauma to the vessel wall. Additionally, it ispossible for the physician to accidentally collapse or displace thedeployed filter should the guide wire twist when the interventionaldevice is being delivered over the guide wire. Moreover, a shockwave(vibratory motion) caused by the exchange of the delivery catheter orinterventional devices along the guide wire can ajar the deployedfiltering device and can possibly result in trauma to the blood vessel.These types of occurrences during the interventional procedure areundesirable since they can cause trauma to the vessel which isdetrimental to the patient's health and/or cause the deployed filter tobe displaced within the vessel which may result in some embolic debrisflowing past the filter into the downstream vessels.

What has been needed is a reliable filtering device and system for usewhen treating stenosis in blood vessels which helps prevent the riskassociated when embolic debris that can cause blockage in vessels atdownstream locations is released into the bloodstream. The device shouldbe capable of filtering any embolic debris which may be released intothe bloodstream during the treatment and safely contain the debris untilthe filtering device is to be collapsed and removed from the patient'svasculature. The device should be relatively easy for a physician to useand should provide a failsafe filtering device which captures andremoves any embolic debris from the bloodstream. Moreover, such a deviceshould be relatively easy to deploy and remove from the patient'svasculature. The inventions disclosed herein satisfy these and otherneeds.

SUMMARY OF THE INVENTION

The present invention provides a number of filtering devices and systemsfor capturing embolic debris in a blood vessel created during theperformance of a therapeutic interventional procedure, such as a balloonangioplasty or stenting procedure, in order to prevent the embolicdebris from blocking blood vessels downstream from the interventionalsite. The devices and systems of the present invention are particularlyuseful while performing an interventional procedure in criticalarteries, such as the carotid arteries, in which vital downstream bloodvessels can easily become blocked with embolic debris, including themain blood vessels leading to the brain. When used in carotidprocedures, the present invention minimizes the potential for a strokeoccurring during the procedure. As a result, the present inventionprovides the physician with a higher degree of confidence that embolicdebris is being properly collected and removed from the patient'svasculature during the interventional procedure.

An embolic protection device and system made in accordance with thepresent invention includes an expandable filtering assembly which isaffixed to the distal end of a tubular shaft member, such as a guidewire. The filtering assembly includes an expandable strut assembly madefrom a self-expanding material, such as nickel-titanium (NiTi) alloy orspring steel, and includes a number of outwardly extending struts whichare capable of self-expanding from a contracted or collapsed position toan expanded or deployed position within the patient's vasculature. Afilter element made from an embolic capturing media is attached to theexpandable strut assembly and moves from the collapsed position to theexpanded position via the movement of the expandable struts. Thisexpandable strut assembly is affixed to the guide wire in such a mannerthat the entire filtering assembly rotates or “spins” freely on theguide wire to prevent the filtering assembly from being rotated afterbeing deployed within the patient's vasculature. In this manner, anyaccidental or intentional rotation of the proximal end of the guide wireis not translated to the deployed filtering assembly, which will remainstationary within the patient's vasculature and, as such, the threat oftrauma to the vessel wall and displacement of the filter caused by therotation and/or manipulation of the guide wire can be virtuallyeliminated.

The expandable struts of the strut assembly can be biased to remain intheir expanded position until an external force placed on the struts tocollapse and maintain the struts in their contracted or collapsedposition is removed. This is done through the use of a restrainingsheath which is placed over the filtering assembly in a coaxial fashionto maintain the strut assembly in its collapsed position. The compositeguide wire and filtering assembly, with the restraining sheath placedover the filtering assembly, can then be placed into the patient'svasculature. Once the physician properly manipulates the guide wire intothe target area, the restraining sheath can be retracted off of theexpandable strut assembly to deploy the struts into their expandedposition. This can be easily performed by the physician by simplyretracting the proximal end of the restraining sheath (which is locatedoutside of the patient) along the guide wire. Once the restrainingsheath is retracted, the self-expanding properties of the strut assemblycause the struts to move radially outward away from the guide wire tocontact the wall of the blood vessel. Again, as the struts expandradially, so does the filter element which will now be in place tocollect any embolic debris that may be released into the bloodstream asthe physician performs the interventional procedure. The filtersub-assembly could be bonded to the core wire at both distal andproximal ends of the embolic protection device. The core wire could bemade from stainless steel or shaped memory biocompatible materials. Theguide wire with the embolic protection device could be loaded into adelivery sheath. The delivery sheath could be torqued, steering thedevice into the intended vessel site.

The filtering assembly can be rotatably affixed to the guide wire byrotatably attaching the proximal end of the filtering assembly to theguide wire. The distal end of the strut assembly can move longitudinallyalong the guide wire and is also rotatable on the guide wire as well.This allows the strut assembly to move between its collapsed andexpanded positions while still allowing the entire filtering assembly tofreely rotate or “spin” about the guide wire. This attachment of theproximal end of the strut assembly to the guide wire allows therestraining sheath to be retracted from the filtering assembly andpermits a recovery sheath to be placed over the expanded strut assemblyto move the strut assembly back to the collapsed position when theembolic protection device is to be removed from the patient'svasculature.

The filtering assembly also may include a dampening element or memberwhich is utilized to absorb some of the shockwave (vibratory motion)that may be transmitted along the length of the guide wire during thehandling of the guide wire by the physician. Since a sudden shock to thefiltering assembly can cause the filter to scrape the wall of the bloodvessel or become displaced in the vessel, the dampening member acts muchlike a “shock absorber” to absorb some of the shock and prevent thetransmission of the shock force to the filtering assembly. This shockcan be produced via a number of way, for example, through the exchangeof interventional devices along the guide wire. Also, when therestraining sheath is removed from the filtering assembly, a shockwavecan be created if the self-expanding struts open too quickly. As aresult of utilizing the dampening member, shock and trauma to thepatient's vasculature are minimized and the chances of displacing thefilter are virtually eliminated. In one aspect of the dampening member,a helical spring is formed on the proximal end of the expandable strutassembly to provide dampening to the assembly. Other methods ofobtaining dampening can be utilized, such as attaching a separatelyformed spring or elastomeric member to the strut assembly.

The expandable strut assembly made in accordance with the presentinvention may be made from a length of tubing (also known as a“hypotube”) made from a shape memory alloy or other self-deployingmaterial. Stainless steel or other biocompatible metals or polymers canbe utilized to form the struts of the assembly. Another material isnickel-titanium (NiTi). The individual struts of the expandable strutassembly are formed on the length of hypotube by selectively removingmaterial from the tubing to form the particular size and shape of thestrut. For example, the wall of the hypotube can be laser cut with slotsto form the individual struts. Small tabs can also be lazed into thetubing along the strut which can be used to hold the filter member inplace. By selectively removing portions of the hypotube by a highprecision laser, similar to lasers utilized in the manufacturer ofstents, one can achieve a very precise and well defined strut shape andlength. In one aspect of the present invention, the pattern of thematerial to be removed from the hypotubing can be a repeatingdiamond-shaped which creates a strut pattern in the form of two invertedtriangles meshed together. This particular strut pattern providesgreater strength along the strut where it would have a tendency to breakor become weakened. Such a strut pattern also provides for a morenatural bending position for each strut, allowing the expandable strutassembly to open and close more uniformly. In one particular pattern,the strut pattern requires the removal of a repeating truncated diamondpattern by laser or other means to create the shape of the strut. Inthis particular pattern, each strut has a relatively straight centersection formed between two inverted triangles, somewhat similar to thestrut pattern described above. This particular strut pattern provides anexpanded center section which allows the struts to expand to a greatervolume, which helps in the capture of emboli by allowing a larger filterto be placed on the strut assembly. The center section located betweenthe two inverted triangle also provides a sufficient working area toattach the filter element onto the strut assembly. These same featurescan be accomplished by curved sections which have a reduced width in thecenter section.

The embolic protection device may also include a filtering assembly witha strut assembly which is not self-expanding, but utilizes theapplication of a force on the proximal and distal ends of the strutassembly to deploy and collapsed the assembly. In this particular formof the invention, the embolic protection device includes an inner shaftmember and an outer tubular member which is coaxially disposed over theinner shaft member. The distal end of the expandable strut assembly canbe attached to the inner shaft member with the proximal end of the strutassembly being attached to the distal end of the outer tubular member.When there is relative movement between the inner shaft member and outertubular member, a force is created which is imparted to the expandablestrut assembly to cause the struts to either contract or expand. Forexample, when the outer tubular member and inner shaft member are movedrelative to each other to produce an inward force acting on the proximaland distal ends of the strut assembly, the force causes the expandablestruts to move from the collapsed position into the expanded position.Thereafter, when the strut assembly is to be collapsed, the outertubular member and inner shaft member can be moved relative to eachother to create an outward force acting on the proximal and distal endof the strut assembly to cause the expanded struts to move back to theircollapsed position. A physician easily can manipulate the proximal endsof the inner shaft member and outer tubular member to deploy andcollapse the filtering assembly as needed. The filtering assembly couldbe self-expanding with the movement of the inner and outer membersproviding the means for expanding and collapsing the assembly withoutthe need for an outer sheath.

The inner shaft member can be a guide wire which can be utilized to movethe filtering assembly directly into position downstream from the lesionfor capturing any embolic debris which may be released into thebloodstream. The inner shaft member could also be a elongated tubularmember which has an inner lumen that can track along a guide wire oncethe guide wire has been maneuvered into position into the patient'svasculature. The entire embolic protection device can then be deliveredto the desired location over the guide wire using over-the-wiretechniques.

The filtering element utilized in conjunction with the embolicprotection device can take on many different forms as are disclosedherein. In one aspect, the filter includes a proximal cone section whichexpands to the diameter of the artery in which the embolic protectiondevice is to be deployed. This proximal cone section funnels blood flowand embolic debris into a main or central filter located distal to theproximal cone section. This proximal cone may or may not providefiltering itself. Its primary function is flow direction and its abilityto collapse and expand with the expandable struts of the strut assembly.A main or central filter may comprise an elongated tubular shaped memberis located distal to the proximal cone section. It is integral with thedistal end of the proximal cone section and provides a large filteringarea that acts as a storage reservoir for holding embolic material.Ideally, it is sized so that it receives any and all of the embolicmaterial which it is to be filtered by the embolic protection device. Itincludes a number of perfusion openings which allow blood to passthrough but retain embolic material. The central filter may not becollapsible or expandable, but rather may be made somewhat rigid and hasan outer diameter large enough to provide a storage reservoir forholding embolic material yet can be withdrawn and delivered through theparticular guiding catheter utilized to deploy the embolic protectiondevice into the patient's vasculature. The central filter also could bemade from collapsible material, but should have an outer diameter whichis large enough to provide an adequate storage reservoir yet can bewithdrawn through the guiding catheter as well. Although this centralfilter may have a substantially fixed diameter, it can also be taperedand should have an outer diameter small enough to fit through the innerdiameter of the specific guiding catheter utilized to deploy the device.

As with all of the filter elements made in accordance with the presentinvention, the material which can be utilized includes a variety ofmaterials such as polymeric material which is foldable and recoverselastically to aid in the capture of the emboli trapped in the filter.Other suitable materials include braided or woven bio-compatiblematerial which can significantly filter the desired size of the embolicdebris to be captured by the filter. The filter can be formed by blowinga suitable material into the proposed shape and then cutting offunwanted portions. The perfusion openings can be drilled into thematerial using a laser, such as an excimer laser, or by mechanicallydrilling and punching the openings to the desired size and shape. Laserdrilling of the holes provides accuracy, quickness and the ability todrill complex hole shapes, circles, ovals and slots. Alternatively, thecentral filter can be made from the same or different material from theproximal cone portion and can be welded or bonded to create an integralunit.

Still another type of filter material can be utilized in accordance withthe present invention which does not require the use of mechanicaldrilling or laser cutting to create the precise openings in the filterwhich allows adequate blood perfusion while capturing the desired sizeof embolic debris. This filtering material utilizes an open-celledmicroporous structure which has uniform porosity and a network-likestructure which traps embolic particles. Such filtering material has thebenefit of being both mechanically strong and more tear resistant whilebeing most effective in trapping embolic debris since the particles musttravel through an intricate network of patterns in order to escapethrough the filter. Due to the open-celled microporous structure, theprobability that embolic debris will somehow escape through thestructure is extremely minimal.

The method for making this open-celled microporous filtering materialconsists of dissolving a selected polymer into a solvent to produce apolymer/solvent solution. This polymer/solvent solution is then cast orsprayed as a film into the desired shape and thickness. For example, thefilm can be cast onto a cone-shaped rotating mandrel which improves theuniformity of the film thickness. Then, a non-solvent is cast or sprayedonto the film before complete evaporation of the solvent. Thisnon-solvent induces a phase-separation of the polymer to create themicroporous structures. The resulting microporous material can then beplaced onto the strut assembly to create the composite emboli-catchingdevice.

In one particular filter made in accordance with the present invention,the proximal cone includes advantageous features which help prevent thefilter from slipping off the expandable strut assembly. These featuresalso help to prevent trapped embolic debris from being squeezed out ofthe filter as the filter is being collapsed for removal from thepatient's vasculature. The filter may include, for example, a set ofrestraining straps designed to be attached to each of the proximal endsof the struts to help secure the filter onto the strut assembly. Thesestraps can include tabs which can be wrapped around each of the strutsand permanently affixed thereto utilizing a suitable adhesive. Theproximal cone section of the filter may also include a number ofindented flaps which cooperate to close off the inlet opening of thecentral filter. These indented flaps are formed on the proximal cone andmove into position to cover the opening of the central filter when theproximal cone section is collapsed by the strut assembly. Therefore, thepossibility that any embolic debris trapped within the deep reservoir ofthe central filter will be discharged through the inlet opening isgreatly diminished since the opening will be closed off by theseindented flaps. Likewise, the proximal cone section of the filter canalso include inwardly inverting flaps located near the inlet opening ofthe proximal cone section which cooperate to close off the large inletopening of the proximal cone section whenever the strut assembly iscollapsed. These elements help to prevent accidental leakage of trappedembolic debris whenever the filtering assembly is collapsed for removalfrom the patient.

In other aspects of the present invention, variations can be made to thedevices described above which enhance their performance characteristics.For example, a strut assembly can be utilized which utilizes strutshaving different lengths which allows greater ease in re-sheathing theexpanded strut/filter assembly since the filter and struts can beincrementally introduced into the restraining sheath, rather than havingthe struts and filter material enter the sheath all at once. Likewise,the filter itself can be made with a proximal edge which has a scallopedpattern which helps prevent the filter material from entering into thesheath all at once. As a result, the filtering assembly can be moreeasily retracted by the recovery sheath and collapsed to its smallerprofile when the device is to be removed from the patient's vasculature.

Other advantages associated with the present invention include theplacement of a surface coating on the strut of the strut assembly forreducing the coefficient of friction at selected areas of the strutassembly to help prevent possible embolic material from sticking tostruts. Embolic debris which does not make its way into the filter andbecomes “stuck” on proximal struts of the filter assembly can possiblybe released into the bloodstream when the filter assembly is beingcollapsed and withdrawn from the patient's vasculature. In one aspect,selective deposition of a slippery polymer to the proximal struts of thestrut assembly can be utilized to reduce the coefficient of frictionbetween the embolic debris and the struts. This helps allow the embolicmaterial to be less likely to stick on a strut assembly and more likelyto pass into the filter. High areas of strain of the strut assembly maycause the coating material to crack if the coating is not sufficientlyelastic. Additionally, high strain regions of the device would not becoated if the coating would affect the performance of the expansion ofthe strut assembly. Such materials includes polyimide and PTFE coatings,which can be applied to a strut assembly without affecting themechanical properties of the base material. In another aspect of theinvention, a coating of “slippery” polymer deposited on the entire strutassembly provided that the polymer was sufficiently elastic so as not tocrack or affect the ability of the struts to bend throughout the device.

These and other advantages of the present invention will become moreapparent from the following detailed description of the invention, whentaken in conjunction with the accompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view, partially in cross section, of an embolicprotection device embodying features of the present invention showingthe expandable filtering assembly in its collapsed position within arestraining sheath and disposed within a vessel.

FIG. 2 is an elevational view, partially in cross section, similar tothat shown in FIG. 1, wherein the expandable filtering assembly is inits expanded position within the vessel.

FIG. 3 is a perspective view of the strut assembly which forms part ofthe filtering assembly of the present invention as shown in itscollapsed position.

FIG. 4 is a plan view of a flattened section of the expandable strutassembly shown in FIG. 3 which illustrates one particular strut patternfor the expandable strut assembly.

FIG. 5 is a perspective view of another embodiment of an expandablestrut assembly which forms part of the filtering assembly of the presentinvention in its collapsed position.

FIG. 6 is a plan view of a flattened section of the expandable strutassembly of FIG. 5 which shows an alternative strut pattern for theexpandable strut assembly.

FIG. 7 is an elevational view, partially in cross section, of theproximal end of the expandable strut assembly of FIG. 2 as it isrotatably attached to the guide wire.

FIG. 8 is an elevational view, partially in section and fragmented,showing the distal end of the filtering assembly of FIG. 2 as it isslidably mounted on the guide wire.

FIG. 9 is a perspective view of another embodiment of an embolicprotection device made in accordance with the present invention.

FIG. 10 is a elevational view of the various components making up theembolic protection device of FIG. 9.

FIG. 11 is an elevational view of the embolic protection device of FIG.9 in its expanded position.

FIG. 12 is an end view of the filter element of the embolic protectivedevice of FIG. 11 taken along lines 12—12.

FIG. 13 is an end view of the filtering element of FIG. 12 which showsthe retaining tabs of the filter prior to being wrapped around thestruts of the expandable strut assembly to help retain the filer elementon the strut assembly.

FIG. 14 is an end view, similar to that shown in FIG. 12, of anotherembodiment of the filter element of the embolic protection device whichshows an alternative embodiment of retaining tabs and structuralelements that can be used to help retain the filter element on the strutassembly.

FIG. 15 is an end view of the filter element of FIG. 14, showing theretaining tabs of the filter element prior to being wrapped around thestruts of the expandable strut assembly to help retain the filterelement on the strut assembly.

FIG. 16 is a cross sectional view of the central filter of the filteringdevice of FIG. 11 taken along lines 16—16.

FIG. 17 is an elevational view, partially in cross-section andfragmented, of the embolic protection device of FIG. 11 showing theindented flaps of the proximal cone section in the expanded position.

FIG. 18 is an elevational view, partially in cross-section andfragmented, showing the indented flaps of the proximal cone section inthe collapsed position which causes the indented flaps to close theinlet opening of the central filter of the device.

FIG. 19 is a perspective view of an embolic protection device made inaccordance with the present invention which includes inverted flapswhich help close the inlet opening of the proximal cone section of thefilter element when the device is collapsed.

FIG. 20 is an elevational view, partially in cross-section andfragmented, of the embolic protection device of FIG. 19 showing theproximal cone section and inverted flaps in an expanded position.

FIG. 21 is an elevational view, partially in cross-section andfragmented, of the embolic protection device of FIG. 19 wherein theproximal cone section is collapsed which causes the inverted flaps toclose off the inlet opening of the proximal cone section of the filterelement.

FIG. 22 is a perspective view of an alternative embodiment of a filterelement made in accordance with the present invention.

FIG. 23 is an elevational view of the various components which make upanother embodiment of an embolic protection device made in accordancewith the present invention.

FIG. 24 is an elevational view depicting the embolic protection deviceof FIG. 23 in the expanded position.

FIG. 25 is an elevational view of the various components which make upanother embodiment of an embolic protection device made in accordancewith the present invention.

FIG. 26 is an elevated view depicting the embolic protection device ofFIG. 25 in the expanded position.

FIG. 27 is an elevational view, partially in section, depicting theembolic protection device of FIG. 25 in a collapsed position anddisposed within a vessel.

FIG. 28 is an elevational view, partially in section, similar to thatshown in FIG. 27, wherein the embolic protection device is expandedwithin the vessel.

FIG. 29 is another embodiment of an embolic protection device made inaccordance with the present invention.

FIG. 30 is an elevational view, partially in section, of the embolicprotection device of FIG. 29 in its expanded condition within a vessel.

FIG. 31 is another embodiment of an embolic filtering device made inaccordance with the present invention.

FIG. 32 is an elevational view, partially in section, of the embolicfiltering device of FIG. 31 in its expanded condition and disposedwithin a vessel.

FIG. 33 is an elevational view of the various components making upanother embodiment of an embolic protection device made in accordancewith the present invention.

FIG. 34 is an elevational view depicting the embolic protection deviceof FIG. 33 in its expanded position.

FIG. 35 is an elevational view depicting the embolic protection deviceof FIG. 34 in its collapsed position.

FIG. 36 is an elevational view, partially in section, of an alternativeembodiment of an embolic protection device similar to that shown in FIG.34.

FIG. 37 is an elevational view of two deployment members which move thestruts of the strut assembly into the expanded or collapsed positions.

FIG. 38 is an end view of the filtering assembly of FIG. 34 taken alonglines 38—38.

FIG. 39A is an elevational view depicting an alternative strut assemblymade in accordance with the present invention which allows the assemblyto be collapsed to a lower profile.

FIG. 39B is an elevational view depicting an alternative strut assemblymade in accordance with the present invention which allows the assemblyto be collapsed to a lower profile.

FIG. 40 is an expanded side view showing the arrangement of struts onthe strut assembly of FIG. 39.

FIG. 41 is an alternative embodiment of a filter assembly with analternative filter element made in accordance with the presentinvention.

FIG. 42 is an enlarged side view of the filter element of the filteringassembly of FIG. 41.

FIG. 43 is an elevational view of a proximal locking mechanism which canbe utilized in accordance with embodiments of the embolic protectiondevice made in accordance with the present invention.

FIG. 44 is an elevational view, partially in section, showing thebiasing spring of the locking mechanism of FIG. 39 which can maintainthe embolic protection device either in the collapsed or expandedposition.

FIG. 45 is an elevational view of the various components making upanother embodiment of an embolic protection device made in accordancewith the present invention.

FIG. 46 is an elevational view depicting the embolic protection deviceof FIG. 45 in its expanded position.

FIG. 47 is an elevation view depicting the embolic protection device ofFIG. 46 as it is being moved into its collapsed position.

FIG. 48 is a cross-sectional view of the embolic protection device ofFIG. 46.

FIG. 49 is an elevational view of another embodiment of the embolicprotection device made in accordance with the present invention.

FIG. 50 is a cross-sectional view depicting the embolic protectiondevice of FIG. 49 in its expanded position.

FIG. 51 is an elevational view, partially in cross-section, showing analternative way to rotatably mount the filter assembly of FIG. 49 to theguide wire.

FIG. 52 is an elevational view of another embodiment of the embolicprotection device make in accordance with the present invention.

FIG. 53 is a cross-sectional view showing the distal end of the embolicprotection device of FIG. 52.

FIG. 54 is an elevational view of another embodiment of an embolicprotection device made in accordance with the present invention.

FIG. 55 is an elevational view, partially in cross-section, similar tothat shown in FIG. 54, wherein the expandable filtering assembly is inits collapsed position.

FIG. 56 is a cross-sectional view of the embolic protection device ofFIG. 54 taken along line 56—56.

FIG. 57 is an elevational view of a proximal end of an expandable strutassembly showing a dampening member associated with a filtering assemblywhich is rotatably attached to a guide wire.

FIG. 58 is a cross-sectional view of the proximal end of a filteringassembly made in accordance with the present invention showing oneparticular example of attaching an obturator to a strut assembly.

FIG. 59 is an elevational view depicting an embolic protection devicemade in accordance with the present invention which includes a coatingthat reduces the frictional coefficient between embolic debris and thestruts of the strut assembly to help prevent embolic particles fromsticking to the strut assemblies.

FIG. 60 is a schematic elevational view of a rotating mandrel utilizedto create an open-celled microporous filtering material made inaccordance with the present invention.

FIG. 61 is an elevational view of another embodiment of an embolicprotection device embodying features of the present invention showingthe expandable filter assembly in its collapsed position within arestraining sheath.

FIG. 62 is an elevational view, partially in cross-section, similar tothat shown in FIG. 61, wherein the expandable filtering assembly is inits expanded position outside of the restraining sheath.

FIG. 63 is an elevational view, partially in cross-section, similar tothat shown in FIG. 62, wherein an actuating member is being utilized toretract the expanded filtering assembly shown in FIG. 62 to itscollapsed position.

FIG. 64 is an elevational view depicting the embolic protection deviceof FIG. 63 as it is being moved into a restraining sheath.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to the drawings, in which like reference numerals representlike or corresponding elements in the drawings, FIGS. 1 and 2 illustratean embolic protection device 10 incorporating features of the presentinvention. In the particular embodiment shown in FIGS. 1 and 2, theembolic protection device 10 comprises a filtering or filter assembly 12which includes an expandable strut assembly 14 and a filter element 16.The filter assembly 12 is rotatably mounted on the distal end of anelongated tubular shaft, such as a guide wire 18. Additional detailsregarding particular structure and shape of the various elements makingup the filter assembly 12 are provided below.

The embolic protection device 10 is shown as it is placed within anartery 20 or other blood vessel of the patient. This portion of theartery 20 has an area of treatment 22 in which atherosclerotic plaque 24has built up against the inside wall 26 of the artery 20. The filterassembly 12 is placed distal to, and downstream from, the area oftreatment 22 as is shown in FIGS. 1 and 2. Although not shown, a balloonangioplasty catheter can be introduced within the patient's vasculaturein a conventional SELDINGER technique through a guiding catheter (notshown). The guide wire 18 is disposed through the area of treatment andthe dilatation catheter can be advanced over the guide wire 18 withinthe artery 20 until the balloon portion is directly in the area oftreatment. The balloon of the dilatation catheter can be expanded,expanding the plaque 24 against the inside wall 26 of the artery 20 toexpand the artery and reduce the blockage in the vessel at the positionof the plaque 24. After the dilatation catheter is removed from thepatient's vasculature, a stent 25 (shown in FIG. 2) could also bedelivered to the area of treatment 22 using over-the-wire techniques tohelp hold and maintain this portion of the artery 20 and help preventrestenosis from occurring in the area of treatment. Any embolic debris27 which is created during the interventional procedure will be releasedinto the bloodstream and will enter the filtering assembly 12 locateddownstream from the area of treatment 22. Once the procedure iscompleted, the filtering assembly 12 is collapsed and removed from thepatient's vasculature, taking with it all embolic debris trapped withinthe filter element 16.

One particular form of the expandable strut assembly 14 is shown inFIGS. 1-4. As can be seen in these figures, the expandable strutassembly 14 includes a plurality of radially expandable struts 28 whichcan move from a compressed or collapsed position as shown in FIG. 1 toan expanded or deployed position shown in FIG. 2. FIG. 3 shows a lengthof tubing 30 which can be utilized to form this expandable strutassembly 14.

The expandable strut assembly 14 includes a proximal end 32 which isrotatably attached to the guide wire 18 and a distal end 34 which isfree to slide longitudinally along the guide wire 18 and also can rotatethereabout. The distal end 34 moves longitudinally along the guide wirewhenever the struts move between the expanded and contrasted positions.The proximal end 32 includes a short tubular segment or sleeve 36 whichhas a coil spring formed therein which acts as a dampening member orelement 38. The function of this dampening element 38 will be explainedbelow. The distal end 34 of the tubing 30 also includes a short segmentor sleeve 40 which is slidably and rotatably disposed on the guide wire18.

Referring now to FIGS. 1, 2 and 7, the proximal end 32 of the expandablestrut assembly 14 is mounted between a tapered fitting 42 locatedproximal to the dampening element 38 and a radiopaque marker band 44located distal to the proximal end 32. The tapered end fitting 42 andmarker band 44 fix the proximal end 32 onto the guide wire 18 to preventany longitudinal motion of the proximal end along the guide wire butallow for rotation of the proximal end 32 and the filtering assembly 12.This particular construction allows the expandable strut assembly torotate or “spin” freely about the guide wire. In this manner, thefiltering assembly 12 will remain stationary should the guide wire 18 berotated at its proximal end after the embolic detection device 10 hasbeen deployed within the patient's vasculature. This is just one way ofaffixing the expandable strut assembly 14 onto the guide wire 18 toallow it to spin or rotate on the guide wire 18. Other ways ofperforming this same function can be employed with the presentinvention.

The benefits of mounting the proximal end 32 of the expandable strutassembly 14 to the guide wire 18 include the ability to precisely deploythe filtering assembly 12 within the artery once the guide wire 18 hasbeen positioned in the patient's vasculature. Since the proximal end 32cannot move longitudinally along the guide wire, the physician can besure that the filtering element 12 will be placed exactly where he/sheplaces it once the restraining sheath 46 is retracted to allow theexpandable struts to move into their expanded position. Additionally,since the proximal end 32 is affixed to the guide wire, any movement ofthe filtering element as the restraining sheath 46 is retracted shouldnot occur. Since the expandable struts 28 can be made fromself-expanding materials, there may be some stored energy in thefiltering assembly 12 as it is held in its collapsed position by therestraining sheath 46. As that restraining sheath 46 is retracted, therecan be a frictional build-up which can cause the strut assembly 14 tomove outward if the proximal end 32 were not affixed to the guide wire18. As a result, if the ends of the strut assembly 14 were not somehowfixed onto the guide wire, there could be a tendency of the filteringelement 12 to spring out of the restraining sheath 46 as it is beingretracted. As a result, the placement of the filtering element 12 willnot be as accurate since the physician will not be able to predetermineif and how much the filtering assembly 12 would move as the restrainingsheath 46 is retracted.

The dampening element 38, which in this particular embodiment of theinvention is shown as a helical coil formed on the proximal end 32 ofthe strut assembly 14, helps to dampen any shockwaves (vibratory motion)which may be transmitted along the guide wire 18, for example, wheninterventional devices are being delivered or exchanged over the guidewire in an over-the-wire fashion. Similarly, this dampening element 38also helps dampen any shock forces which may result as the restrainingsheath 46 is retracted to allow the radial expandable struts to moveinto their expanded position as shown in FIG. 2. The helical coil canalso act as an attachment method which helps retain guide wireflexibility. The dampening element 38 should somewhat also dampen shockwhich may be created as the recovery sheath 48 (FIG. 2) contacts thestruts to collapse the filter assembly 12 when the embolic protectiondevice is to be removed from the patient's vasculature. As a result,this dampening element 38 will absorb and dissipate forces which wouldotherwise act on the expanded filtering assembly 12 and could cause theassembly 12 to scrape the inside wall 26 of the artery 20 or otherwisecause trauma to the vessel. This dampening element 38 also helps preventdisplacement or misalignment of the filter element within the arterywhich may result from a sudden shock transmitted along the guide wire18.

The filter element 16 utilized in conjunction with this preferredembodiment of the invention includes a tapered or cone shaped section 50which has a plurality of openings 52 which allow the blood to flowthrough the filter 16 but captures emboli within the inside of the coneshaped section. The filter element 16 includes a short proximal section52 which is integral with the cone shaped section 50 and expands to asubstantially cylindrical shape when the struts 28 of the strut assembly14 are deployed. The inlet opening 51 allows any embolic debris 27 toenter the filter element 16 for capture. This short cylindrical section52 also serves as a suitable location where the filter element 16 can beadhesively or otherwise affixed to each strut 28 of the strut assembly14. The filter element 18 includes a short distal cylindrical section 54which is integral with the remaining sections of the filter and isattached to the sleeve segment 40 which forms the distal end 34 of theexpandable strut assembly 14. This distal cylindrical section 54 can beattached to the sleeve 40 using adhesives or other bonding techniques.

Referring again to FIG. 1, the filter assembly 12 is maintained in itscollapsed or compressed position through the use of a restraining sheath46 which contacts the struts 28 and filter elements 16 to maintain thefiltering assembly 12 collapsed. Although not shown, the guide wire andrestraining sheath 46 have proximal ends which extend outside thepatient. The struts 28 can be manipulated into the expanded position byretracting the restraining sheath 46 (via its proximal end) to exposethe struts 28. Since the struts 28 are self expanding, the removal ofthe restraining sheath 46 allows the struts 28 and filter element 16 tomove to the expanded position within the artery 20.

The guide wire 18 includes a small sphere 56 affixed thereto which isbeneficial during the delivery of the embolic protection device 10 intothe patient's vasculature. This sphere 56 is approximately as large asthe inner diameter of the restraining sheath 46 and is utilized as a“nosecone” to prevent possible “snow plowing” of the embolic protectiondevice as it is being delivered through the patient's arteries. Thesphere 56 is atraumatic and has a smooth surface to help the embolicprotection device travel through the patient's vasculature and crosslesions without causing the distal end of the restraining sheath 46 to“dig” or “snow plow” into the wall of the arteries. When the embolicprotection device 10 is to be removed from the patient's vasculature, arecovery catheter 48 is utilized to collapse and recover the filterassembly 12. (FIG. 2). Generally, this recovery sheath 48 has a slightlylarger inner diameter than the restraining sheath 46 since the struts 28are now deployed and may require some increased hoop strength at thedistal end 47 of the recovery sheath 48 to properly move the strutassembly 14 back into its collapsed position. The collapse of theexpandable strut assembly 14 can be accomplished by holding the guidewire 18 and moving the proximal end (not shown) of the recovery sheath48 forward which will move the distal end 47 of the sheath 48 over thestruts 28. Alternatively, the recovery sheath 48 can be held stationarywhile the proximal end of the guide wire is retracted back to pull theentire filter assembly 12 into the sheath 48. Upon collapse of thefilter assembly 12, any embolic debris generated and entering thebloodstream during the interventional procedure will remain trappedinside the filter element 16 and will be withdrawn from the bloodstreamwhen the embolic protection device 10 is removed from the patient'svasculature.

A radiopaque marker 58 located approximately at the longitudinal centerof the expandable strut assembly 14 is also affixed to the guide wire 18to provide the physician with a reference marker when positioning thedevice within the patient's artery 20.

The number of struts 28 formed on the expandable strut assembly 14 canbe any number which will provide sufficient expandability within theartery to properly deploy and maintain the filter element 16 in place.In the embodiment shown in FIGS. 1 and 2, the expandable strut assemblyhas four self-expanding struts 28. Likewise, the particular size andshape of each strut 28 can be varied without departing from the spiritand scope of the present invention. In this preferred embodiment, thestrut pattern includes a first portion 60 having an inverted triangularshape, a substantially straight center section 62, and a second invertedtriangular shaped section 64 which completes the strut. This particularstrut pattern is preferred since the design provides greater strength inregions of the strut where there would be a tendency for the strut tobreak or become weakened. These regions include the very proximal anddistal ends of each strut which are designed with a wider base. Thisparticular design also allows the composite strut assembly to open andclose more uniformly which is beneficial especially when collapsing thestruts for removal from the patient. Additionally, the center section 62allows the struts 28 to expand to a greater volume, which allows alarger filter element to be placed on the strut assembly 14, if needed.

Referring now specifically to FIG. 4, a plan view of a rolled out flatsheet of the tubing 30 utilized to form the struts 28 is shown. As canbe seen from FIG. 5, a particular design pattern is cut into wall of thetubing 30 in order to form each strut 28. In the case of the embodimentshown in FIG. 3, that pattern consists of a truncated diamond shape 65which helps form the first section 60, the center section 62 and thesecond section 64. By selectively removing portions of the tubing 30through laser cutting or other suitable means, each particular strut 28can be made to a precise shape, width and length. This truncated diamondpattern 68 repeats as can be seen in FIG. 4 to provide uniform size toeach of the struts 28 formed therein.

An alternative preferred embodiment of the expandable strut assembly 14is shown in FIGS. 5 and 6. This particular strut assembly 14 is similarto the one shown in FIGS. 3 and 4 except that there is no centersection. The struts 68 shown in FIGS. 5 and 6 consist of a pair ofinverted triangles which form a first section 70 and a second section72. The plan view of the flat sheet of the tubing 30 used to form thestrut assembly 14, as shown in FIG. 6, shows a repeating diamond pattern74 which is cut into the tubing to create each individual strut 28.Again, this particular pattern is preferred since greater strength isprovided near the proximal and distal ends of each strut where therewould be a tendency for breakage or a weakness of the strut. When theparticular pattern is cut into the tubing, whether it be the patternshown in FIGS. 3-4 or 5-6 or some other pattern, the sleeve 36 whichforms the proximal end 32 of the strut assembly 14 can thereafter besimilarly cut to create the helical coil which forms the damping element38 on the strut assembly 14.

Another embodiment of the present invention is shown in FIGS. 9-11. Ascan be seen in FIG. 9, the embolic protection device 100 includes afilter assembly 102 having an expandable strut assembly 104 and a uniquefilter element 106. The particular strut assembly 104 utilized with thisembolic protection device 100 is similar to the structure of theexpandable strut assembly 14 shown in the previous embodiment. Thefilter element 106, which will be described in greater detail below, isutilized in its expanded position to collect any embolic debris forremoval from the blood stream of the patient.

The various elements making up this particular embodiment of the embolicprotection device 100 are shown in FIG. 10. In this particularembodiment, the strut assembly 104 does not necessarily have to be madefrom a self-expanding material, as the strut assembly 14 disclosed inthe previous embodiment. Rather, it could be made from stainless steelor other materials which require the application of external axial forceon the proximal end 110 and distal end 112 of the strut assembly 104 tomove the struts 108 between the contracted and expanded positions. As isshown in FIGS. 10 and 11, the proximal end 110 of the assembly 104includes a short tubular or sleeve-like segment 114 and a similar distalsegment 116. The struts 108 are moved from a contracted to a deployedposition by imparting an inward axial force on the proximal end 110 anddistal end 112 of the strut assembly 104. This can be accomplished byfirst attaching the distal end 112 of the assembly 104 directly to theguide wire 118. The proximal end 110 of the strut assembly 104, canthen, in turn, be attached to an outer tubular member 120 which, alongwith the guide wire 118, has a proximal end which extends outside of thepatient. The proximal ends (not shown) of both the outer tubular member120 and the guide wire 118 can be manipulated by the physician to eitherimpart an inward axial force on the two ends 110 and 112 of the strutassembly 104 to move the struts 108 to the deploy position or can bemoved to impart an outward axial force on both ends 110 and 112 tocollapse the struts 108 back to their collapsed position.

The struts 108 of the strut assembly 104 can be made from a piece oftubing (hypotube) in which select portions of the tubing are removed toform the particular size and shape of each strut. The strut assembly 104could also be made from a self-expanding material such asnickel-titanium (NiTi) if desired. The struts 108 would then be biasedinto either the collapsed or expanded position with the outer tubularmember 120 being used to move the proximal end 110 in order to expand orcontract the strut assembly 104, depending upon, of course, the mannerin which the expandable struts 108 are biased. Again, in the embodimentshown in FIG. 10, the struts 108 have a similar shape as the struts 28shown in the embodiment of FIGS. 14. This particular embodiment of anembolic protection device thus eliminates the need to utilize both arestraining sheath and recovery sheath which would be otherwise neededin order to deploy and contract the embolic protection device. Thisparticular design, however, does not allow for the filter assembly 102to rotate as freely along the guide wire 118 as does the previousembodiments, although there can be some rotation. However, the outertubular member 120 and guide wire 118 are utilized in a similar fashionby allowing interventional devices to be delivered over the outertubular member in an over-the-wire fashion after the embolic protectiondevice 110 is in place within the patient's vasculature.

It should be appreciated that the strut assembly 104 could also be madefrom a self-expanding material which maintains the struts 108 biased intheir expanded position. The outer tubular member 120 would still beutilized in order to move the expanded struts 108 back into theircollapsed position. The proximal ends of the outer tubular member 120and guide wire 118 can be attached to a simple locking mechanism 600(shown in FIGS. 39 and 40) which can be utilized to move the outertubular member relative to the guide wire for maintaining the strutassembly 104 in its collapsed position until ready to be deployed withinthe patient's vasculature. It should further be appreciated that theparticular embolic protection device 100 can also be modified toeliminate the outer tubular member 120 and be a self-expanding assemblylike the one shown in FIGS. 1-2. In such a case, the proximal end 110 ofthe strut assembly 104 can be rotatably attached to the guide wire 118with the distal end 112 being slidably mounted on the guide wire toallow for longitudinal motion and rotational motion about the guide wire118.

The filter element 106 utilized in conjunction with this particularembodiment, or which can be utilized with any of the other embodimentsdisclosed herein, has a unique shape to provide a large reservoir tocollect and maintain any embolic debris which may be trapped within thefilter 106. Referring now to FIGS. 9-12, the various sections of thefilter element 106 will be described in greater detail. It should benoted that the filter element 122 of FIG. 22 incorporates many of thesame filter sections as the filter element 106 shown in FIGS. 10-12.Therefore, corresponding sections of these filters will be describedsimultaneously in order to better understand the principles underlyingthese unique filter elements. Both filter elements include a proximalcone section 124 which expands to fit within the diameter of the artery.This particular proximal cone section 124 blocks or funnels blood flowand embolic debris into the main or central filter 126. In both of thefilter elements shown in FIGS. 9 and 22, the proximal cone section 124includes a plurality of openings 128 which are utilized in filtering theembolic debris. However, it is possible to eliminate the openings 128 onthe proximal cone section 124 to allow it to primarily direct blood flowand embolic debris directly into the central filter 126. This centralfilter 126 is integral with the proximal cone section 124 and includes anumber of openings 128 utilized to permit blood flow through thissection of the filter but to retain any embolic debris which is largerthan the size of the openings 128. The openings 128 can be laser cut orotherwise punched into this central filter 126. This central filter 126has a substantially cylindrical shape and acts as a large reservoir forholding the embolic debris. Ideally, it is sized such that when it iscompletely full of embolic material, it does not collapse to a smallerprofile. However, is should be able to be withdrawn into the guidingcatheter (not shown) when in its fully expanded condition with embolicdebris trapped therein. Thus, the maximum outer expanded diameter ofthis central filter 126 should be smaller than the inner diameter of theguiding or sheath utilized in deploying the embolic protection device100 in the patient's vasculature. The central filter can be made from astiffer polymeric material which will maintain the shape and outerdiameter to prevent the filter from collapsing after use. The resultingstiffer central filter cannot be squeezed during the collapse andremoval of the filtering assembly from the artery which should preventany trapped embolic debris from being squeezed out of the reservoirportion of the central filter.

Both filters 106 and 122 include a distal tapered region 130 whichtapers down to the shaft of the guide wire 118. The taper of thisparticular region of the filter elements 106 and 122 facilitates thedelivery of the embolic protection device 100 and helps prevent the“snow plow” effect when being delivered through the patient'svasculature. There is a small distal section 132 which also forms a partof the filter element and is utilized to attach the distal end of thefilter directly onto the guide wire. This distal section 132 can befastened utilizing well-known adhesives or other bonding techniques topermanently affix it to the guide wire 118 and prevent any embolicdebris from escaping through the distal opening of this distal section132.

The primary benefit of utilizing a large central filter with a proximalcone section is that there is a large filtering area provided by thecentral filter 126 which is less likely to squeeze out trapped embolicdebris when the embolic protection device 100 is being removed from thepatient's vasculature. As can be seen in FIG. 22, the central filter 126has a general cylindrical shape while the central filter 126 of FIG. 9can be a generally cylindrically shaped but can also include sidecreases 134 which produce a unique-looking design. The particularcross-sectional view of the central filter 126 of filter element 106 isshown in FIG. 16 and shows just one of a number of different shapes thatcan be used to create the central filter 126. In use, the filter element122 of FIG. 22 would be attached to the strut assembly 104 and guidewire 118 utilizing adhesives or other bonding techniques.

The filter element 106 of FIG. 9 also incorporates some unique featureswhich are not shown in the more basic filter design shown in FIG. 22.These advantages include the unique cross-sectional shape of the centralfilter 126 shown in FIG. 16, along with other features which helpmaintain the filter element 106 securely attached to the struts 108 ofthe strut assembly 104. Referring again to FIGS. 10-12, the filterelement 106 includes a short outer rim 136 which is proximal to the endof the cone section 124 and has a large inlet opening 125 for receivingthe blood flow and any embolic debris released into the bloodstream.This proximal outer rim 136 is ring-shaped and can be utilized to helpattach the filter onto the struts 108 of the assembly 104. As can beseen in FIG. 10, this proximal outer ring is attached to the middlesection 138 of each strut 108 and includes a tab 123 which can bewrapped around and attached to the strut 108. This proximal outer ring136 also helps maintain the circular inlet opening 125 which must beexpanded and maintained within the artery of the patient. Attached tothe front of the outer rim 136 are restraining straps 142 which arelikewise utilized to help hold the filter onto the struts 108 of theassembly 104. Each restraining strap 142 includes tab-like projections144 which can wrap around each individual strut and be affixed theretoutilizing a bonding agent such as adhesive. These elements allow therestraining straps 142 to hold the filter element 106 onto the strutassembly 104. It should be appreciated that any number of differenttab-like projections 144 can be utilized in conjunction with theserestraining straps 142 to help secure the filter onto the assembly 104.The proximal end of each restraining strap 144 is attached to a sleeve146 which also can be adhesively fixed to the tubular segment 114 formedat the proximal end 110 of the strut assembly 104. These varioussections of the filter 106 can be made as one composite unit and can beformed by cutting a pattern into a pre-formed filter blank. Thereafter,the openings 128 along the length of the filter element 106 can beplaced accordingly.

The proximal cone section 126 of the filter element 106 shown in FIG. 9includes a plurality of indented flaps 148 which are utilized to helpclose the opening of the central filter 126 when the proximal cone 124is in its collapsed position. Each of these indented flaps 148, as shownin FIGS. 11, 17 and 18, are created such that as the proximal conesection 124 is being closed, the flaps join together and cooperate toform a barrier which prevents embolic debris from being released throughthe inlet opening 127 of the central filter 126. In the particularembodiment shown in FIG. 9, four such indented flaps can be utilized(only two of which are shown in FIGS. 11, 17 and 18) in order to createthe barrier necessary to close the opening to the central filter 126.However, the number of indented flaps 148 and the size and shape of eachflap 148 can be varied accordingly in order to create a protectivebarrier which helps prevent trapped embolic debris from escaping fromthe central filter 126 as the device 100 is being collapsed for removalfrom the patient.

Referring now to the FIGS. 19, 20 and 21, a variation of the indentedflaps 148 is shown in the proximal cone section 124 of the filterelement 106. As can be seen in these figures, there are a pair of flapportions 150 which are located within the proximal cone section 124 andare utilized as a mechanism for closing the inlet opening 127 of thefilter element 106 when the filter assembly is collapsed. These flapportions 150 act much like the indented flaps 148 in that as theproximal cone section 124 is being collapsed, these flap portions 150extend across the inlet opening 127 of the filter element 106 to createa barrier which helps prevent trapped embolic debris from being releasedback into the bloodstream. These flap portions 150 can be smallappropriately shaped pieces which extend across the inlet opening whenthe filter is expanded but do not interfere with the flow of blood goinginto the filter element 106. Blood simply travels around the flapportions 150, along with any embolic debris, to the center filter 126where the embolic debris will be trapped in the debris reservoir. Thisfeature provides a preventive measure to diminish the possible releaseof trapped embolic debris when the embolic protection device 100 isbeing collapsed and removed from the patient's vasculature.

Referring now to FIGS. 14 and 15, an alternative form of the restrainingstraps and tabs which are utilized to affix the filter element 106 isshown. In these particular figures, the restraining strap 152 extendsalong each strut 108 and a tab like projection 154 is utilized to affixthe restraining strap to each individual strut 108. Additional lateralstrapping members 156 which extend laterally from each restraining strap152 can also be utilized to help prevent the filter element 106 frommoving off the strut assembly 104 during usage. These various designsshows alternative ways of affixing the filter element 106 onto the strutassembly 104. It should be appreciated that still other forms ofattaching the filter element 106 to the strut assembly 104 can beutilized without departing from the spirit and scope of the presentinvention.

Another embodiment of the present invention is shown in FIGS. 23 and 24.In this particular embodiment, the embolic protection device 200includes a filter assembly 202 having a strut assembly 204 and a filterelement 206. The strut assembly 204 is similar to the strut assemblyshown in FIGS. 1-4. It includes self-expanding struts 208 which areexpandable from a collapsed position to a fully expanded position. Thisstrut assembly 204 includes a proximal end 210 and a distal end 212.This strut assembly 204 can be made from a piece of tubing in which thestruts are created by selectively removing portions of the tubing. Inthis particular embodiment, the tubing can be hypotubing made from ashape memory material such as nickel-titanium (NiTi). The resultingstrut assembly 204 is normally biased to remain in the expanded positionand require the applications of force on the ends 210 and 212 to deploythe struts 208 back to their collapsed position.

The proximal end 210 includes a segment of tubing 214 and the distal end212 includes a similar segment of tubing 216 as well. The distal end 212is permanently attached to the guide wire 218 near the distal coil 220of the guide wire. The distal end 212 can be bonded using adhesives orwelded, brazed or soldered to the guide wire 218. Likewise, the proximalend 210 of the strut assembly 204 can be bonded, welded, brazed orsoldered to an elongated outer tubular member 222 which has a proximalend which extends outside of the patient. The proximal ends of theelongated tubular member 222 and the guide wire 218 can be manipulatedby the physician to either open or close the filter assembly 202. Asuitable locking mechanism 600 for maintaining the strut assembly 204 inits collapsed or closed position is disclosed in FIGS. 43 and 44 and isdescribed in greater detail below.

The filter element 206 comprises of a cone shape portion 224 which isattached to the center section 226 of each strut 208. A plurality ofopenings 228 are laser cut or otherwise formed in the filter 206 whichallows blood to flow through the filter but captures embolic debriswhich is larger than the size of the openings. This is another moreexample of a variation of the embolic protection device which can bemade in accordance with the present invention.

Another embodiment of the present invention is shown as a embolicprotection device 300 in FIGS. 25-28. Like the other embodiments, thisdevice 300 includes a filtering assembly 302 which has an expandablestrut assembly 304 and a filter element 306 attached to the strutassembly 304. Individual struts 308 are formed on the strut assembly 304for moving the filtering element 306 into an expanded position withinthe patient's vasculature. The strut assembly 304 is some what similarsimilar to the previous embodiments disclosed above in that an outerelongated tubular member 310 is utilized in conjunction with a guidewire 312 to collapse and deploy the strut assembly 304. Although notshown in FIGS. 25 and 26, the outer tubular member 310 has a proximalend which extends with the proximal end of the guide wire outside of thepatient to allow the physician to move the proximal ends to deploy orcollapse the filtering assembly 302. The strut assembly 304 can beformed by selectively removing material from the outer tubular member310 near its distal end to create the individual struts 308. The strutswill open upon application of an inward force on ends of the individualstruts 308. Alternatively, the strut assembly 304 can be made from apiece of hypotubing which can be affixed to the outer tubular member 310as is shown in some of the previous embodiments of the invention. Theentire outer tubular member 310 with the strut assembly 304 is free toslide along the length of the guide wire 312 which allows the filteringassembly 302 to be positioned within the patient's vasculature in anover-the-wire fashion.

As can be seen in FIGS. 25-28, a stop element 320 is located near thedistal coil 322 of the guide wire 312. This distal stop element 320 isutilized in conjunction with the outer tubular member 310 to produce theforce necessary to expand the struts 308 into the expanded position. Theembolic protection device 300 can be utilized in the following matter.First, the physician maneuvers the guide wire 312 into position past thelesion or area of treatment. Thereafter, the outer tubular member 310with the strut assembly 304 is advanced over the guide wire 312 in anover-the-wire technique. The embolic protection device 300 remains inits collapsed position while being delivered over the guide wire 312 tothe distal end 313 of the guide wire, as is shown in FIG. 27.Thereafter, the physician allows the distal sleeve 312 of the outertubular member 310 to contact the stop element 320 located on the guidewire 312. By applying additional force at the proximal end of theelongated tubular member 310, the physician will cause the struts 308 toexpand radially outward for deployment within the artery. The resultingexpansion of the struts 308 thereby opens up the filter element 306within the artery. The physician can then deliver interventional debrisinto the area of treatment and perform the procedure on the lesion. Anyembolic debris which may be created during the interventional procedurewill be collected within the interior of the filter 306.

A simple locking mechanism 600 device located at the proximal end of theouter tubular member and guide wire, as is shown in FIGS. 43 and 44, canbe utilized to move and maintain the strut assembly 304 in the expandedcondition. Thereafter, once the embolic protection device 300 is desiredto be removed from the vasculature, the physician merely retracts theproximal end of the outer tubular member 310 to remove the force on thestrut assembly 304 allowing the struts 308 to move back to the collapsedposition. Thereafter, the embolic protection device 300 and guide wire312 can be removed from the patient's vasculature.

The filter element 306 takes on a some what different shape from theprevious filter element in that the main portion of the filter element306 has a shape of a half of a dilatation balloon utilized inangioplasty procedures. Perfusion openings 313 are located on the filterelements 306 for allowing blood perfusion while capturing embolicdebris. The proximal end of the filter element 306 includes a pluralityof restraining straps 314 which extend to a proximal sleeve 316 which isaffixed to the outer tubular member 310 proximal of the struts 308. Thedistal end 318 of the filter element 306 is also attached to the distalsleeve 321 which is formed on the outer tubular member 310 when thestruts 308 are formed.

FIGS. 29 and 30 show another embodiment of a embolic protection device400 made in accordance with the present invention. This particularembodiment is somewhat similar to the previous embodiments in that anexternal force is generated on the ends of the struts of the strutassembly to facilitate the outward expansion and inward contraction ofthe struts. Referring specifically now to FIG. 29, the embolicprotection device 400 includes a filter assembly 402 having a strutassembly 404 which has a filter element 406 attached thereto. Theindividual struts 408 are formed on an outer tubular member 410 whichhas a distal end 412 attached to the distal end 413 of an inner tubularmember 414. Both the inner member 414 and the outer member 410 haveproximal ends which are located outside of the patient's vasculature.The struts 408 are radially expanded by moving the outer tubular member410 relative to the inner tubular member 414 to apply the necessaryaxial force to cause the struts to deploy outward. An opposite axialforce is necessary to cause the struts 408 to move back to the collapsedposition when the device is to be removed from the patient'svasculature. In this embodiment, more than four struts 408 are used toexpand the filter element 406 within the artery 420. Again, the number,size and shape of the struts 408 can be varied without departing fromthe spirit and scope of the present invention.

The filter element 406 also has the shape of one half of a dilatationballoon utilized in angioplasty procedures and includes openings 416which allows blood to flow through the filter but captures the desiredsize of the embolic debris. The proximal end of the filter element 406which includes an inlet opening 417 is attached to each of the centersections 418 of the struts 408. The distal end 420 of the filter 406 isattached to the distal end 412 of the strut assembly 404.

The lumen 422 of the inner tubular member 414 can be utilized for anumber of purposes, such as blood perfusion past the deployed filterassembly 402 when placed in the artery. Therefore, should the openings416 of the filter element 406 become clogged with debris which preventsblood from flowing through the filter, oxygenated blood can be perfusedto downstream vessels via the inner lumen of the inner tubular member414. This lumen can also be utilized for delivering the embolicprotection device 404 over a guide wire in an over-the-wire fashion.

FIG. 31 and 32 show a variation of the previous filter element which canbe utilized in conjunction with the present invention. The filterembolic protection device 400 is basically the same device shown inFIGS. 29 and 30 except that the filter element 430 has a differentdesign. As can be seen in FIG. 31, the filter element 430 includes aproximal cone shape portion 431 which extends in front of the inletopening 432 of the filter element 430. This type of filter 430 hasadvantages in that it may be easier to attach to the strut assembly 404.Additionally, the wall of the artery is insulated from the struts 408 byrestraining straps 434. This device also has the benefits of being lowprofile and allows the use of any guide wire, as well as allowing forguide wire exchanges. This particular embodiment, like the previousembodiments, allows for the exchange of the interventional device in anover-the-wire procedure.

Referring now to FIGS. 33-38, two different embodiments of the presentinvention are shown which utilize a different mechanism for deployingthe struts of the strut assembly. In FIG. 33, an embolic protectiondevice 500 is shown as including a filter assembly 502 having anexpandable strut assembly 504 and a filter element 506. As with theother embodiments, the strut assembly 504 includes a plurality ofradially expandable struts 508 which are utilized to place the filterelement 506 into an expanded position within the patient's vasculature.The mechanism for deploying the radially expandable struts 508 utilizesa number of self-expanding deployment members 510 which are attached toeach of the struts 508 making up the expandable strut assembly 504. Theself-expanding deployment members 510 are made from self-expandingmaterials, such as nickel-titanium alloy, which can be compressed to avery small profile and expanded to a rather large expanded positionwhich moves the struts 508 and filter 506 to the fully expandedposition. As is seen in FIGS. 33 and 34, there are a number ofdeployment members 510 which are located along the length of each of thestruts 508. There is a proximal set 512 of deployment members 510located along the proximal region of each strut 508. There is a centerset 514 of deployment members 510 located at the center section of eachstent 508. As can be seen in FIG. 34, the coverage of the filter element506 begins at this center set 514. A third or distal set 516 ofdeployment members 510 is located on the struts in the region where thefilter element 506 is placed to enhance the deployment of each strut.

As can be seen in FIG. 37, each deployment member 510 is basically acollapsible piece of self-expanding material which will expand to afinal size when fully deployed. FIG. 38 shows an end view of the centerset 514 and distal set 516 of the deployment members as they are locatedalong the struts 508. Each of the sets of deployment members 510 willfully expand to a quarter-circle segment which cooperate to form a“ring” when the sets of the deployment members are fully expanded. As aresult of using this particular construction, the filter element 506will fully deploy and maintain a circular-shaped opening 507 which willcontact the wall of the artery when the embolic protection device 500 isdeployed within the patient's vasculature.

In the first embodiment of this particular embolic protection device500, the distal end 518 of the expandable strut assembly 504 ispermanently attached to the guide wire 520. The proximal end 522 of thestrut assembly 504 is, in turn, attached to an elongated outer tubularmember 524 which has a proximal end (not shown) which extends outside ofthe patient's vasculature along with the proximal end of the guide wire.The embolic protection device 500 can be moved into its collapsedposition as shown in FIG. 35 by simply retracting the proximal end ofthe outer tubular member 524 to impart an outward force on the ends ofthe strut assembly 504. The force which will be imparted on the ends ofthe strut assembly 504 should be sufficient to collapse each deploymentmembers 510 which will, in turn, cause each of the struts 508 to moveback to the collapsed position. As with the other embodiments, once thestruts 508 are placed in its collapsed position, the filter element 506will likewise collapse and will trap and encapsulate any embolic debriswhich may have been trapped within the filter element 506.

Referring now to FIG. 36, an alternative embodiment of an embolicprotection device similar to the one shown in FIG. 33 is disclosed. Thisparticular embolic protection device 530 utilized the same filterassembly 502 and strut assembly 504 as shown in the previous embodiment.The differences between the strut assembly 532 of the embolic protectiondevice 530 includes the elimination of the proximal set 512 ofdeployment members 510 from this strut assembly 532. Otherwise, thefilter assembly 534 is virtually the same as the filter assembly 502 ofthe previous device 500.

The distal end 518 of the strut assembly 534 is also permanently affixedto the guide wire 520 in this particular embodiment. The proximal end ofthis particular strut assembly 534 is free to move longitudinally alongthe length of the guide wire when being moved from a deployed to acontracted position and visa versa. The mechanism for deploying thefilter assembly 532 is restraining sheath 536 which places a force onthe and deployment members 510 which prevent them from expanding untilthe restraining sheath 536 is retracted. Once the embolic protectiondevice 530 is properly in place within the patient's vasculature, theproximal end (not shown) of the restraining sheath 536 is retracted toallow the deployment members 510 to open the struts 508 and filterelement 506 to the fully expanded position within the artery. When thedevice is to be removed from the patient's vasculature, the restrainingsheath 536 is placed against the proximal region 535 of the struts 508and is retracted over the struts to force the deployment members 510back into their collapsed position. Thereafter, any embolic debris whichmay be trapped within the filter element 506 is retained and safelyremoved from the patient's vasculature. A proximal set of deploymentmembers 510 may not have to be used with this particular embodimentsince there may be a need to reduce the amount of expansive forceapplied to the struts in this proximal region 535. However, it is stillpossible to place a first set of deployment members at this proximalregion 535 provided that the sheath has sufficient strength to collapsethe struts in this region.

The filter element 506 shown in FIGS. 33-38 is made from a mesh materialwhich allows blood to perfuse therethrough but captures embolicmaterial. The mesh material can be made from any interwoven fabric whichcontains small size openings which will trap the desired size of emboli.Alternatively, the filter 506 can be made from a polymeric material withperfusion openings found therein.

Referring now to FIGS. 39A, 39B and 40, an alternative strut assembly550 which could be utilized in conjunction with any of the filteringassemblies made in accordance with the present invention is shown. Thestrut assembly 550 includes struts 552 and a deployment member 554 whichis used to expand the struts 552 into the deployed expanded position.This deployment member 554 acts in the same manner as the previouslydescribed deployment members in that the deployment member 554 can bemade from a self-expanding material which will expand to a final sizeonce fully deployed. The deployment member 554 also could be collapsedto an unexpanded position when an external force is placed on theassembly to maintain the deployment member 554 in its collapsedposition. As can be seen in FIGS. 39A, 39B and 40, the deployment member554 has a serpentine pattern made of peaks 556 and valleys 558 which areaccordingly attached to the struts 552 of the assembly 550. In theseparticular embodiment of the invention, the deployment member 554 has asinusoidal wave pattern which includes the peaks 556 and valleys 558that are attached to the ends of the struts 552. This particular patternallows the struts to be offset or staggered from one another to allowthe assembly 550 to be collapsed to a lower profile which enhances theassembly's ability to reach tighter lesions and to be maneuvered intoeven distal anatomy. The staggered strut design also increases theassembly's flexibility which enhances the ability to move the assemblywithin the patient's anatomy. A filter element could be likewise placedover or within the struts 552 to create a composite filter assembly. Thedeployment member 554 provides complete vessel wall opposition, forcinga seal of the filter edge to the wall of the vessel. The deploymentmember 554 can have multiple geometries without departing from thespirit and scope of the present invention. This particular strutassembly 550 also could be created from a lazed hypotube whichincorporates the staggered strut design. The number of struts can bevaried along with the particular lengths of the struts. Alternatively,the deployment member 554 could be made from a separate piece ofmaterial from the struts and could be attached using methods such assoldering, brazing or bonding, using suitable adhesives. As can be seenfrom FIGS. 39A and 39B, the attachment of the struts 552 to the peaks556 and valleys 558 of the deployment 554 can be varied as shown. Bothof these particular designs allow the strut assembly to be collapsed toa low profile.

Referring now to FIGS. 41 and 42, an alternative filter element 570 withan angulated filter edge 572 is shown which is used to help in theloading and retrieval of the embolic protection device into arestraining sheath. The filter element 570 is similar to the filterspreviously described in that the filter element 570 includes a centralsection 574 which has a plurality of openings 576 that are utilized infiltering the embolic debris. The filter element 570 includes an edge572 which is configured similar to a crown, with pointed peaks 578 andvalleys 580. This configuration of the filter edge 572 allows the filterto be incrementally introduced into the restraining sheath, thuspreventing the material from entering the sheath all at once. As can beseen in FIGS. 41 and 42, the edge 572 has a somewhat sinusoidalconfiguration which would reduce the stress concentration in the valleyregions 580 of the filter. The peaks 578 of the filtering element 570would be matched up with the struts 582 of the strut assembly 584. Thenumber of peaks 578 could vary with the number of struts 582 on thestrut assembly 584. In this particular embodiment, the filtering element570 could be placed within the inside of the strut assembly 584, or,alternatively, the filter could be placed on the outside of the assembly584. It should be appreciated that other filter elements describedherein also could either replace on the inside or outside of the strutassembly used in connection with a particular filtering assembly. As thestrut assembly 584 is being loaded or retrieved, the peaks 578 of thefilter element 570 would enter the restraining sheath first. Thisprevents all of the filtering material from entering the sheath at once,causing a gradual and incremental loading of the filter element 570 intothe sheath. Additionally, dimensions A and B shown in FIG. 42 show thedifference in the valley depths in the sinusoidal pattern of the filteredge 572. This allows for a variety of configurations. One possibleconfiguration is A=B=0. Additionally, B≧A≧0 so that the loading of thefilter into the sheath will be in a smooth operation. This particularconfiguration eliminates or virtually eliminates all of the valleyportions 580 from entering the sheath at the same time. The filter edge572 may or may not have openings 576. The peaks 578 can also havevarying heights. Dimensions C, D and E shown in FIG. 42 shows adifference in the peak heights on the sinusoidal pattern of the filteredge 572. This particular pattern also allows for a variety ofconfigurations. One possible configuration is C=D=E=0. Additionally,E≧D≧C≧0 to correspond, or alternatively, not to correspond with thedepths of the valleys 580.

Referring now to FIGS. 45-48, an alternative embodiment of an embolicprotection device 640 is disclosed. This particular embolic protectiondevice 640 utilizes a filter assembly 642 and strut assembly 644 whichis somewhat similar to the strut assembly 550 shown in FIG. 39B. Theparticular strut assembly 644 includes a set of proximal struts 646attached to a deployment member 648 which moves between an unexpanded orcollapsed position and an expanded position in the same manner as thepreviously described deployment members. This deployment member 648 canbe made from a self-expanding material which will expand to a finaldiameter once fully deployed. This deployment member 648 is collapsiblewhen a sheath or sleeve is placed over the assembly. A set of distalstruts 650 are attached to the deployment member 648 and also areexpandable and collapsible with the deployment member 648. Thedeployment member 648 has a substantial V-shaped wave pattern whichpermits the strut assembly to more easily collapse to a low profile. Afilter element 652 is attached to the strut assembly 644 and has a shapemuch like the filter element 570 shown in FIGS. 41 and 42. The filterelement 652 includes an edge portion 654 which is configured withalternating peaks 656 and valleys 658. This configuration of the filteredge portion 654 also allows the filter to be incrementally introducedinto the restraining sheath 660, thus preventing the filtering materialfrom entering the sheath 660 all at once. As can be seen in FIGS. 45 and46, the filter element 652 has a somewhat tulip-like shape due to theconstruction of the peaks 656 and valleys 658. As is shown in FIG. 46,the peaks 656 of the filter element 652 are matched up with the wavepattern of the deployment member 648 and are attached thereto usingadhesives or other bonding techniques. The filter can extend along andoutside the struts with the edge portion 654 adhesively attached to theinside edge of the deployment member 648.

The filter element 652 can be made from a mesh material which allowsblood to profuse therethrough but captures embolic material. The meshmaterial can be made from interwoven fabric which contains small sizeopenings which would trap the desired size of emboli. Alternatively, thefilter element 652 can be made from a polymeric material with profusionopenings formed therein.

In this particular embodiment of the embolic protection device 640, anobturator 662 is located at the distal end 664 of the filter assembly642 and is utilized for obtaining smooth deployment through thepatient's vasculature. This particular obturator 662 acts much like thesphere 56 shown in FIGS. 1 and 2 which prevents “snow plowing” of theembolic protection device as it is being delivered through the patient'sarteries. This obturator 662 also has a smooth surface which tapers froma smaller diameter distally to a larger diameter that corresponds to theouter diameter of the restraining sheath 660. A smooth outer surface iscreated when the obturator 662 and restraining sheath 660 are placedadjacent to each other. This obturator can be made from a material suchas PEBAX 40D, or other polymeric materials or alloys which are capableof performing the desired function.

As is shown in the cross-sectional view of the device in FIG. 48, theobturator 660 is attached (via adhesive or other bonding material) to atubular member 666, which is made from a material such as polyimidetubing. This tubular member 666 is adhesively or otherwise attached tothe distal ends 668 of the distal struts 650. The tubular member 666 isnot, however, adhesively attached to the guide wire 672, but rather, isallowed to rotate free around the coils 670. The obturator 662 alsoextends over a portion of the coils 670 of the guide wire 672 and isfree to rotate about the coils 670. The proximal end 674 of the filterassembly 642 is attached to the guide wire 672 in such a manner to allowit to rotate freely about or “spin” on the guide wire 672 as well. Thefilter assembly 642 is attached to the guide wire 672 much like theembodiment shown in FIGS. 1 and 2. As can be seen in FIGS. 46 and 48, astop fitting 676 is attached to the guide wire 672 to prevent theproximal end 674 from moving past that particular fitting. A second stopfitting 678, located within the filter assembly 642, helps prevent thefilter assembly 642 from moving axially any substantial distance alongthe guide wire 672.

The proximal ends 680 of the proximal struts 646 are attached to a pairof tubular segments 682 and 684 which are in a coaxial relationship. Amarker band (not shown) can be partially sandwiched between these twotubular segments 682 and 684 to provide the physician with a referencewhen placing the embolic protection device 640 in the patient'svasculature. The tubular segments 682 and 684 are adhesively affixed toeach other and the marker band to form a composite tubular extensionmember 686. This composite tubular extension member 686 extends betweenthe two stop fittings 676 and 678. The extension member 686 may includea dampening element 679 which is formed on a portion of the segment tohelp dampen some of the vibratory motion which may be transmitted alongthe guide wire 672. It can be cut into the extension member 686 muchlike the dampening element 38 is cut on the embodiment shown in FIGS.1-3. It should be appreciated that this extension member 686 can beformed from a single piece of tubing and need not be two separatelyformed segments glued together. This extension member 686 also helps toincrease the torque response of the embolic protection device 640 on theguide wire and allows more room for the filter assembly to rotate, ifneeded.

Additional marker bands 688 can be placed on the strut assembly 644 toprovide additional reference sources for the physician to rely on whenmaneuvering the device in the patient's arteries. Like the previouslydescribed filter assemblies, this particular filter assembly 642 willremain in place within the patient's vasculature, once deployed therein,and will remain stationary even if the guide wire 672 is rotated by thephysician during an exchange of interventional devices along the guidewire. As a result, there is less chance of trauma to the patient'sartery at the location where the filter assembly 642 contacts the wallof the artery.

The particular configuration of the filter assembly 642 and itsattachment to the guide wire 672 allows the physician to eliminate anyair bubbles which may be trapped within the restraining sheath 660 as itcovers the filter assembly 642 in its collapsed state. The presentdesign allows the physician to flush a solution, such as saline, throughthe lumen of the restraining sheath 660 out to its distal end to causeany trapped air bubbles to be vented through the distal opening 661 ofthe obturator 662. As a result, the possibility that an air bubblepossibly could be released into the patient's artery can be virtuallyeliminated by thoroughly flushing saline through the restraining sheath660 to eliminate any trapped air bubbles. The tubular member 666 acts asa conduit for the saline to flow out of the obturator 662. Fluid isallowed to flow through the restraining sheath 660 through the innerlumen 688 of the tubular member 666 and out the distal opening 661 ofthe obturator 662.

Referring now to FIGS. 49 and 50, another alternative embodiment of aembolic protection device 690 is shown. In this particular embodiment,the filter assembly 692 includes a strut assembly 694 which includesonly a proximal set of struts 696 that are attached to a deploymentmember 698. This particular filter assembly 692 is somewhat similar tothe assembly shown in FIGS. 45-48, except that a distal set of strutsare not utilized. The filter element 700 is attached directly to thedeployment member 698 and has a distal end 702 which is attached to asegment of tubing 704 made from a material such a polyimide. This tubing704 extends from the proximal end 706 of the filter assembly 692 to thedistal end 702 of the filter 700 and is rotatable on the guide wire 710.

In this particular embodiment, the proximal end 706 of the filterassembly 692 is attached directly to a tubing member 704. The proximalend 706 of the filter assembly 692 terminates in a collar 708 as isshown in FIGS. 49 and 50. It is attached to the tubing 704 usingadhesives or other bonding techniques. This entire filter assembly 692,which includes the tubing member 704, is rotatable upon the guide wire710 to allow the device to remain stationary within the patient's arteryeven if the guide wire is rotated by the physician during a deviceexchange. A stop fitting 712 located on the guide wire 710 acts toprevent the filter assembly 692 from moving axially along the length ofthe guide wire 710. The distal end 714 of tubing member 704 abutsagainst the most proximal coil 716 formed on the guide wire 710. In thismanner, the coil 716 acts as a stop fitting to prevent axial movement ofthe tubing member 704 along the guide wire 710.

The distal end 702 of the filter 700 is attached to the tubing member704 using adhesives or other bonding agents. The distal end 702 of thefilter does not have to be movable axially along the guide wire, as withthe previous embodiments, since the filter 700 itself is pliable andwill move as the strut assembly 694 moves between its expanded andcollapsed positions. When the strut assembly 694 is moved from itsunexpanded to expanded position, the filter 700 will “stretch” somewhatas the deployment member 698 and struts 696 move outward and somewhataway from the distal end 702 of the filter 700. As with the previousembodiments, a restraining sheath (not shown) is utilized to move thefilter assembly 692 between its expanded and unexpanded positions.

Referring now to FIG. 51, an alternative method for mounting the filterassembly 692 to the guide wire 710 is shown. In this particularembodiment, the strut assembly 694 is attached to an outer segment oftubing 704, which can be made from materials such as polyimide. Thisouter tubing 704 is in turn bonded, or otherwise attached to, an innertubing 705 which is slightly shorter than the length of the outer tubing704. For example, the outer tubing 704 and inner tubing 705 can beattached to each other utilizing a suitable adhesive. As can be seen inFIG. 51, the inner tubing 705 has a distal end 707 which abuts againstthe coil of the spring tip 711 of the guide wire 710. This allows aportion of the outer tubing 704 to extend over some of the proximalcoils of the spring tip 711. The proximal ends of the outer tubing 704and inner tubing 705 are adapted to abut the stop fitting 712 located onthe guide wire which also helps prevent the filter assembly 692 frommoving axially along the length of the guide wire. This inner tubing 705can also be made from a number of different materials, includingpolyimide. Also, the length of the inner tubing 704 and outer tubing 705can be adjusted such that the radiopaque spring tip 711 can be used toindicate corresponding device positions under fluoroscopy.

Referring now to FIGS. 51 and 52, a variation of the filter assembly ofFIGS. 49 and 50 is shown. In this particular embodiment, the filterassembly 692 includes a strut assembly 694 in which only a proximal setof struts 696 are attached to a deployment member 698. The filterelement 700 is attached directly to the deployment member 698 and has adistal end which can be attached either directly to the guide wire 710or to a small segment of tubing 713 (FIG. 53) which will allow thefilter element 700 and strut assembly 694 to spin about the guide wire710 in the manner which has been previously described.

In this particular embodiment, the inner tubing upon which thepreviously described embolic protection device 690 is mounted has beenremoved to obtain a slightly lower profile for the composite device. Ascan be seen in FIG. 51, the proximal end 706 of the filter assembly 692terminates at a collar 708 which is directly attached to the guide wire710. A stop fitting 712 located on the guide wire 710 acts to preventthe filter assembly 692 from moving axially along the length of theguide wire.

Referring specifically now to FIG. 53, the distal end 715 of the filterelement 700 includes the short segment of tubing 713 which allows thefilter 700 to spin about the guide wire 710. This particular tubing canbe made from any one of a number of different materials, includingpolyimide. Alternatively, the distal end of the filter 700 could beattached directly to the guide wire utilizing adhesives or other bondingtechniques. The entire filter assembly 692 would still be able to rotateslightly on the guide wire since the filter element 700 can be made froma pliable material which would “twist” to a certain degree on the guidewire. This would still allow the strut assembly 694 to remain stationaryin place within the patient's vasculature in the event that the guidewire is slightly rotated at the proximal end by the physician. Again,the filter element and strut assembly can be made in accordance with themethods described herein.

Referring now to FIGS. 43 and 44, a simple locking mechanism 600 forexpanding and collapsing the filter assembly described herein are shown.These particular mechanisms are useful whenever the embolic protectiondevice utilizes an inner shaft member and outer tubular member formoving the strut assemblies into the expanded or collapsed position.Referring first to FIG. 43, the proximal end 602 of the outer tubularmember 604 is shown with a locking mechanism 600 which can be utilizedto lock the embolic protection device in either an expanded orunexpanded position. The locking mechanism 600 includes an elongatedslot 606 which is cut into the wall of the outer tubular member 604 andincludes a first locking position 608 and a second locking position 610.The inner shaft member 612, which can be either a solid shaft such as aguide wire or a hollow tubular shaft, has a raised dimple 614 whichmoves within this elongated slot 606. This raised dimple 614 can bemoved into either the first locking position 608 or second lockingposition 610 to either maintain the filter assembly in an expanded orunexpanded position. It should be appreciated that only two lockingpositions are shown on this particular embodiment, however, it ispossible to use a number of different locking positions if the userdesires to have several expanded positions. If the filter assembly isself-expanding, then a removable handle that pushes and pulls the innerand outer members could be used. The handle would push/pull the innerand outer members to hold the assembly closed, then be removed so thatother interventional devices could be passed over the inner tubularmember. Thereafter, the handle could be placed back onto the proximalends of the inner and outer members to collapse and remove the filterassembly.

The proximal end 602 of the outer tubular member includes a smallsection of knurling 616, as does the inner shaft member 612, whichprovides the physician with a surface to grip when holding andmaneuvering the proximal ends of these devices. The locking mechanism600 can also include a biasing spring 618 located within the inner lumen620 of the outer tubular member 604 for biasing the inner shaft member612 with an outward force which maintain the raised dimple 614 near thefirst locking position 608. This biasing mechanism includes a shoulderregion 621 located at the proximal end of the outer tubular member and acollar 622 located on the inner shaft member 612. The force of thespring 618 again helps to maintain the dimple 614 at or near the firstlocking position 608. Such a mechanism is preferable when the device isdesigned to be maintained in an unexpanded position until it is ready tobe deployed. It may be beneficial to keep the filter assembly in itsunexpanded position until ready for use since it is possible to causedamage to the filter assembly if left in an expanded position. When thefilter assembly is desired to be placed into the deployed or expandedposition, the physician merely grasps the proximal end of the innershaft member and pulls it back until the dimple 614 is placed into thesecond locking position 610. When the strut assembly is made fromelements which are self-expanding, then there may not be a need to havea biasing spring 618 since the struts on the strut assembly will actsomewhat like a biasing spring to maintain the filter assembly in anexpanded position.

Referring now to FIGS. 54-56, an alternative embodiment of a filterassembly 750 is shown. The filter assembly 750 includes a strut assembly752 which includes a proximal set of struts 754 that are attached to adeployment member 756 which comprises a circumferential range which isintegrally connected to each of the struts 754. A filter 758 is attachedto the deployment member 756 and terminates at a distal end 760 which isslidable along the guide wire 762. A pair of stop fittings 764 and 766allow the composite filter assembly 750 to rotatably spin on the guidewire 762 as has been previously described in connection with otherembodiments disclosed herein.

The lengths of the four individual struts 754 which make up the strutassembly 752 as indicated by arrows l₁, l₂, l₃, and l₄ vary so that asthe filter assembly 750 is being resheathed into the restraining sheath,the filter assembly 750 can be incrementally introduced into therestraining sheath, thus preventing the filter and individual strutsfrom entering the sheath all at once. This particular arrangement helpsin the collapse and resheathing of the filter assembly in the patient'svasculature, especially when the filter portion of the filter assemblyis being resheathed.

As can be seen in FIG. 56, when the filter assembly 750 is expanded, thedeployment member 756 is substantially round and has a slight distal bowwhen viewed longitudinally (as shown in FIG. 54), to facilitatecollapsing of the assembly. In manufacturing this particular strutassembly 752, a tubing of material, such as nitinol, can be laser cutwith the strut assembly heat set in the open (expanded) shape and thendelivered and removed from the patient's vasculature with a low profilesheath. The longitudinal struts that open and employ the filter 758 canbe intrically connected with the circumferential deployment member 756,which as shown in FIGS. 54-56 is a ring that can be cut from the sametubing as the struts. This deployment member 756 would completelycontact with the lumen wall when fully deployed. As the struts arewithdrawn into the sheath, the deployment member between each strut willbe formed by bowing distally convex, as is shown in FIG. 55. Thus, acomplete collapse, the deployment member 756, along with the filter 758,can be drawn into the sheath. Additionally, this deployment member 756can be heat set completely round when fully deployed as is shown in FIG.56.

Referring now to FIG. 57, a dampening element 770, similar to one whichhas been described above, is utilized accordance with a filter assembly772 made in accordance with the present invention. In this particularembodiment, the dampening element 770 is shown as a separate coil springwhich acts as a shock absorber when placed between the proximal end 774of the strut assembly 776 and the proximal stop element 778. Thisparticular arrangement is similar to the one shown in FIGS. 1-2 and 7,except that the dampening element 770 is a separate element from thestrut assembly of 776. In this manner, the dampening element 770 can bemade from a material which is different from the material used to formthe strut assembly 776. This dampening element 770 also will act todissipate at least some of the vibratory motion which may be transmittedalong the guide wire 783.

Referring now to FIG. 58, and also to the particular embodiment shown inFIGS. 45-48, another method for attaching the obturator 660 to the strutassembly 644 is shown. In FIG. 58, the obturator 660 is shown as it isadhesively attached to the strut assembly 644 which allows for greaterbond strength and flexibility during usage. As can be seen in FIG. 58,the distal end of the filter 652 is cut short of the distal end 664 ofthe strut assembly 644 to allow more of the strut assembly 644 to beexposed to the obturator 660. As a result, an adhesive 665 can be placedbetween the obturator 660 to directly contact the strut assembly 644 andachieve a stronger bond. The assembly still includes the tubular member666, which be made from a material such as polyimide, or other suitablematerial, which allows the filter assembly 642 to spin on the guide wire672. Again, the strut assembly 664 itself is bonded to this tubularmember 666 to allow the distal end to spin freely about the guide wire672. The bond strength is maximized through this increased surface areaon the strut assembly 664 which is in direct contact with the obturator660. In one embodiment, the tubular member 666 can extend outapproximately 5 mm from the distal end of the strut assembly 644. Thisshould eliminate any possible contact of adhesive to the guide wire.Again, this construction allows for a smooth rotation of the filter 652on the guide wire. Any excess adhesive from the obturator should collecton the tubing to further increase the bond contact of the obturator tothe filter assembly 642.

One of the requirements of the design of the filter assemblies shown anddescribed herein is that embolic material must pass around proximalstruts of the assembly into the filter portion of the device. Embolicdebris which may collect or “stick” to a proximal strut may pose aproblem when the filter assembly is being collapsed and withdrawn intothe restraining sheath for removal from the patient's vasculature.Should embolic debris collect on a proximal strut, it may not be driveninto the filter assembly for collection and could possibly be releasedinto the patient's blood stream when the filter assembly is beingcollapsed for removal from the patient. In such an event, the physicianmust face the prospect of having to treat possible blockage todownstream vessels caused by such embolic debris.

In order to alleviate or help reduce this unwanted release of embolicdebris from occurring, it is possible to selectively coat the strutassembly with a material which makes the struts “slippery”, i.e.,reduces the coefficient of friction between the embolic debris andstruts, to help reduce the chances of embolic debris sticking to thestruts.

Referring now to FIG. 59, a typical filter assembly 790 is shownincluding a strut assembly 792 which includes proximal struts 794 thatare located upstream from the filter 796. It is in the region of theseproximal struts that one or more pieces of embolic debris can collect,rather than being driven into the filter 796. However, the proximalstruts 794 can be coated with a polymer which reduces the coefficient offriction to help prevent, or at least make it more difficult for,embolic debris to stick onto a strut. For example, a polymer coating canbe placed selectively on these proximal struts. The intent inselectively depositing a slippery polymer coating to these struts is toprevent the coating from extending to areas of the strut assembly whichexperience high strain during device expansion. This may include thedeployment member 798 which helps to deploy the filter 796 during usage.The high strain area of this deployment member may cause certain coatingmaterial to crack if the coating is not sufficiently elastic to“stretch” as the strut assembly expands. Alternatively, a very elasticcoating material could be selected which will allow the entire strutassembly to be coated. Materials of interest include polyimide and PTFEcoatings which could be applied to a nickel titanium strut assemblywithout significantly affecting the mechanical properties of the struts.It should be important to select a polymer coating which reduces thecoefficient of friction yet does not affect the mechanical properties ofthe struts. If the material proves to be too stiff, the performancecharacteristics of the strut assembly could be affected. However, it isstill possible to account for the stiff characteristics of the polymerthrough the strut design, i.e., the struts could be designed to be moreflexible which would offset the stiffness caused by the polymer. Othercoatings which could be utilized include hydrophillic coatings orheparin.

An alternative material for forming the filter used to trap the friableembolic debris utilizes an open-cell microporous material having anetwork-like porous structure that captures the debris. This particularfilter material eliminates the need to either mechanically drill orlaser cut the filter material to create a porous filter which stillallows blood perfusion during the procedure. Use of the filter membranein a microporous structure allows for perfusion and can be mechanicallystrong and more tear resistant than films with direct holes. Thismicroporous structure also allows for more efficient trapping of embolisince the particles of debris have to travel through the intricatepattern of the filter in order to escape. Since a very finemicro-structure can be created, the chances of embolic debris passingthrough the microporous filter are extremely small.

Referring now to FIG. 60, a cone-shaped rotating mandrel 797 is shownthat can be utilized in creating a microporous film/membrane for formingthe filters. The sequence of making the microporous film is a follows,namely, a polymer is first dissolved in a solvent to produce apolymer/solvent solution. This resulting polymer/solvent solution can bethen sprayed or cast into the desired shape and thickness. For example,the film can be sprayed (via a spray nozzle 799 or by other means) onthe rotating mandrel shown in FIG. 60 to create a cone-shaped structure.The rotating mandrel can be made in a number of sizes and shapes tocreate the desired filter element. Rotation of the mandrel usuallyimproves the uniformity of the film thickness. After the polymer/solventsolution is sprayed or cast into the desired shape an thickness, it canthen be either dipped or sprayed with a non-solvent before completeevaporation of the solvent occurs. This non-solvent inducesphaseseparation of the polymer which creates the microporous structuresthroughout the material.

In one example of a microporous polymer film made in accordance with thepresent invention, the film can be made from Tecophilic 60D, a flexiblepolyurethane. Pellets of Tecophilic 60D can be dissolved in THF solvent,and sprayed onto a cone-shaped rotating mandel. The thickness of thefilm can be controlled by several factors, including the concentrationof the solution, the rotational speed of the mandrel, and the amount ofsolution sprayed. After the film is cast, water (a non-solvent) then canbe sprayed on the film to induce phase-separation and create themicroporous structure. The porosity of the Tecophilic 60D film can bevaried by controlling the type of solvent and concentration of thesolvent used. Since this particular process is thermal dynamic, thereshould be no material restrictions. The choice of polymer will dependupon attributes like flexibility and strength of film.

Referring now to FIGS. 61-64, still another embodiment of an embolicprotection device is disclosed. This particular embolic protectiondevice 800 utilizes a filter assembly 802 and a strut assembly 804mounted on the distal end of a guide wire 806. The strut assembly 804 isself-expanding so that a restraining sheath 808 is required to maintainthe assembly in its collapsed position, ready for deployment within thepatient's vasculature.

The strut assembly 804 has a different configuration from the previouslydescribed strut assemblies. As can be seen in FIG. 62, the strutassembly 804 includes several forward radial expandable struts 810 whichextend from the distal end 812 of the filter assembly 802. The forwardstruts 810 help to deploy the filter 814 in the patient's vasculatureduring usage. The forward struts 810 are attached to several activatingstruts 816 which are attached at a collar 818 that is slidable along theguide wire 808. The composite forward struts 810 and activating struts816 provide a mechanism for opening the filter 814 once the restrainingsheath 808 is retracted from the filter assembly 802. The filter 814 canhave an scalloped filter edge 820 which, as described in a previousembodiment above, prevents the entire filter from entering the sheath atthe same time when the device is being collapsed for removal from thepatient's vasculature. A pair of stop fittings 822 and 824, which alsoact as radiopaque markers to assist in locating fluoroscopically withinthe patient, are located at the distal end 812 of the strut assembly 804to attach the assembly to the guide wire 806. This particular designallows the filter assembly 802 to rotate or spin freely around the guidewire 806, while remaining fixed to the guide wire 806.

After the filter assembly 802 has been deployed and it is desired toremove it from the patient's vasculature, an outer tubular member 826(shown in FIG. 63) is utilized to push the activating struts 816 andcollar 818 distally to collapse the strut assembly 804 back to itscollapsed position. This outer tubular member 826 should have sufficientstiffness to push the collar 818 distally along the guide wire 806.After the filter assembly 802 is collapsed, a restraining sheath is usedto resheath the entire device for removal from the patient. (See FIG.64.)

The materials which are utilized to create this particular embodimentare similar to these previously described and include self-expandingmetals and alloys, such as nickel titanium, which can be utilized forthe strut assembly. The filter can likewise be made from materialsdescribed herein. Likewise, the restraining sheath can be made frommaterials described herein, along with any other suitable materials,which should produce a flexible restraining device having sufficienthoop strength to hold the filter assembly in its collapsed position.

The strut assemblies of the present invention can be made in many ways.However, the one particular method of making the strut assembly is tocut a thin-walled tubular member, such as nickel-titanium hypotube, toremove portions of the tubing in the desired pattern for each strut,leaving relatively untouched the portions of the tubing which are toform each strut. The tubing may be cut into the desired pattern by meansof a machine-controlled laser.

The tubing used to make the strut assembly may be made of suitablebiocompatible material such as stainless steel. The stainless steel tubemay be alloy-type: 316L SS, Special Chemistry per ASTM F138-92 or ASTMF139-92 grade 2. Special Chemistry of type 316L per ASTM F138-92 or ASTMF139-92 Stainless Steel for Surgical Implants in weight percent.

The strut size is usually very small, so the tubing from which it ismade must necessarily also have a small diameter. Typically, the tubinghas an outer diameter on the order of about 0.020-0.040 inches in theunexpanded condition. The wall thickness of the tubing is about 0.076 mm(0.003-0.006 inches). For strut assemblies implanted in body lumens,such as PTA applications, the dimensions of the tubing maybecorrespondingly larger. While it is preferred that the strut assembly bemade from laser cut tubing, those skilled in the art will realize thatthe strut assembly can be laser cut from a flat sheet and then rolled upin a cylindrical configuration with the longitudinal edges welded toform a cylindrical member.

Generally, the hypotube is put in a rotatable collet fixture of amachine-controlled apparatus for positioning the tubing relative to alaser. According to machine-encoded instructions, the tubing is thenrotated and moved longitudinally relative to the laser which is alsomachine-controlled. The laser selectively removes the material from thetubing by ablation and a pattern is cut into the tube. The tube istherefore cut into the discrete pattern of the finished struts. Thestrut assembly can thus be laser cut much like a stent is laser cut.Details on how the tubing can be cut by a laser are found in U.S. Pat.No. 5,759,192 (Saunders) and U.S. Pat. No. 5,780,807 (Saunders), whichhave been assigned to Advanced Cardiovascular Systems, Inc. and areincorporated herein by reference in their entirely.

The process of cutting a pattern for the strut assembly into the tubinggenerally is automated except for loading and unloading the length oftubing. For example, a pattern can be cut in tubing using a CNC-opposingcollet fixture for axial rotation of the length of tubing, inconjunction with CNC X/Y table to move the length of tubing axiallyrelative to a machine-controlled laser as described. The entire spacebetween collets can be patterned using the CO₂ or Nd:YAG laser set-up.The program for control of the apparatus is dependent on the particularconfiguration used and the pattern to be ablated in the coding.

A suitable composition of nickel-titanium which can be used tomanufacture the strut assembly of the present invention is approximately55% nickel and 45% titanium (by weight) with trace amounts of otherelements making up about 0.5% of the composition. The austenitetransformation temperature is between about −15° C. and 0° C. in orderto achieve superelasticity. The austenite temperature is measured by thebend and free recovery tangent method. The upper plateau strength isabout a minimum of 60,000 psi with an ultimate tensile strength of aminimum of about 155,000 psi. The permanent set (after applying 8%strain and unloading), is approximately 0.5%. The breaking elongation isa minimum of 10%. It should be appreciated that other compositions ofnickel-titanium can be utilized, as can other self-expanding alloys, toobtain the same features of a self-expanding stent made in accordancewith the present invention.

The strut assembly of the present invention can be laser cut from a tubeof nickel-titanium (Nitinol) whose transformation temperature is belowbody temperature. After the strut pattern is cut into the hypotube, thetubing is expanded and heat treated to be stable at the desired finaldiameter. The heat treatment also controls the transformationtemperature of the strut assembly such that it is super elastic at bodytemperature. The transformation temperature is at or below bodytemperature so that the stent is superelastic at body temperature. Thestrut assembly is usually implanted into the target vessel which issmaller than the diameter if the strut assembly in the expanded positionso that the struts apply a force to the vessel wall to maintain thefilter element in the expanded position.

The piece of tubular hypotube which can be utilized in accordance withthe present invention to form the strut assemblies can be one continuouspiece which forms both the outer tubular member and the strut assemblyas well. In some of the embodiments disclosed herein, the strut assemblyis shown as being made from a short segment of hypotube which isselectively cut to form the strut patterns. Thereafter, the proximal endof the strut assembly is bonded to, either by adhesives, welding,brazing or soldering to the distal end of the outer tubular member.However, these two separate pieces can be formed from a piece of singletubing in a particular embodiment of the invention.

The dampening element which is shown in one of the embodiments of thepresent invention could also be used with any of the other embodimentsdisclosed herein. The dampening element could either be cut into theproximal end of the strut assemblies, as is shown in FIGS. 1 and 2, oran alternative dampening element could be attached to the strutassembly. For example, a separate spring made from a different materialor similar material could be welded, brazed or soldered to the end ofthe strut assembly. Also, other dampening materials could be usedbesides a helical spring in order to achieve dampening. For example, asegment of elastomeric material could be bonded to the strut assembly aswell to act as a “shock absorber” for the system.

The outer tubular member could be made from various materials such asstainless steel, nickel-titanium alloy or materials which have memory.As discussed above, when using a separate outer member attached to thestrut assembly, the distal end can be easily affixed to the strutassembly by known bonding methods. The inner diameter of the outertubular member must of course be comparable to the outer diameter of theinner shaft member to allow the outer tubular member to slide in acoaxial arrangement. The inner shaft member can also be made fromstainless steel, nickel-titanium alloys or shape-memory materials. Inone embodiment, the inner shaft member is shown as a tubular memberwhich has an inner lumen which allows the device to slide over a guidewire in an over-the-wire fashion. Other embodiments show the inner shaftmember as a guide wire or guide wire-like shaft. Generally, when theinner shaft member is utilized as a guide wire, it should include anatraumatic guide wire coil tip to prevent injury to the vessel as theguide wire is being maneuvered through the patient's vasculature. Itshould be appreciated that the coil tip does not have to be placeddirectly next to the filtering assembly in those embodiments whichutilize a guide wire as the inner shaft member. The filtering assemblycould be placed much more proximal to the coil tip to create a short,distal segment of guide wire which may be pre-bent by the physician toaid in steering through the patient's vasculature.

Again, the tubing or hypotube which could be utilized to create thestrut assembly can be a nickel-titanium alloy, such as Nitinol, or othershape-memory materials. It is also possible to utilize stainless steelto form the strut assembly as well. The strut assembly could also bemade from a self-expanding material even in embodiments in which theouter tubular member and inner shaft member are utilized to provide theaxial forces necessary to expand or contract the device during use.Additionally, the strut assembly could be either biased to remain in itscollapsed position or expanded position as may be desired. It should beappreciated that the stent assembly can be made from either pseudoelastic NiTi stressed induced martensite or shape memory NiTi.

One way of making the strut assemblies of the present device is toutilize a shape-memory material,such as nickel titanium, which has thestruts cut utilizing a machine-controlled laser. A tubular piece ofmaterial could be utilized in this process. The strut assembly could bemanufactured to remain in its open position while at body temperatureand would move to its collapsed position upon application of a lowtemperature. One suitable method to allow the strut assembly to assume achange phase which would facilitate the strut and filter assembly beingmounted into the restraining sheath include chilling the filter assemblyin a cooling chamber maintained at a temperature below the martensitefinish temperature through the use of liquid nitrogen. Once the strutassembly is placed in its collapsed state, the restraining sheath can beplaced over the device to prevent the device from expanding once thetemperature is brought up to body temperature. Thereafter, once thedevice is to be utilized, the restraining sheath is simply retracted toallow the filter assembly/strut assembly to move to its expandedposition within the patient's vasculature.

The polymeric material which can be utilized to create the filteringelement include, but is not limited to, polyurethane and Gortex, acommercially available material. Other possible suitable materialsinclude ePTFE. The material can be elastic or non-elastic. The wallthickness of the filtering element can be about 0.00050-0.0050 inches.The wall thickness may vary depending on the particular materialselected. The material can be made into a cone or similarly sized shapeutilizing blow-mold technology. The perfusion openings can be anydifferent shape or size. A laser, a heated rod or other process can beutilized to create to perfusion openings in the filter material. Theholes, would of course be properly sized to catch the particular size ofembolic debris of interest. Holes can be lazed in a spinal pattern withsome similar pattern which will aid in the re-wrapping of the mediaduring closure of the vice. Additionally, the filter material can have a“set” put in it much like the “set” used in dilatation balloons to makethe filter element re-wrap more easily when placed in the collapsedposition.

The materials which can be utilized for the restraining sheath andrecovery sheath can be made from similar polymeric material such ascross-linked HDPE. It can alternatively be made from a material such aspolyolifin which has sufficient strength to hold the compressed strutassembly and has relatively low frictional characteristics to minimizeany friction between the filtering assembly and the sheath. Friction canbe further reduced by applying a coat of silicone lubricant, such asMicroglide®, to the inside surface of the restraining sheath before thesheaths are placed over the filtering assembly.

In view of the foregoing, it is apparent that the system and device ofthe present invention substantially enhance the safety of performingcertain interventional procedures by significantly reducing the risksassociated with embolic material being created and released into thepatient's bloodstream. Further modifications and improvements mayadditionally be made to the system and method disclosed herein withoutdeparting from the scope of the present invention. Accordingly, it isnot intended that the invention be limited, except as by the appendedclaims.

What is claimed:
 1. An embolic protection device for capturing embolicdebris released into a body vessel of a patient, comprising: a shaftmember having a distal and a proximal end; a filtering assembly mountedon the shaft member, the filtering assembly including an expandablestrut assembly and a filter attached to the strut assembly for capturingembolic debris, the expandable strut assembly having a set of proximalstruts, each strut having a first end and a second end; and a deploymentmember having a pattern of alternating peaks and valleys in a wave-likepattern, each of the first ends of the struts being attached to the peakportions of the deployment member, the filter element being attached tothe deployment member and having a filter edge having alternating peaksand valleys in a wave-like pattern corresponding to the pattern of thedeployment member, the filter element being moveable with the struts anddeployment member so that at least a portion thereof contacts the wallof the vessel to capture embolic debris released into the body vessel,wherein the second end of each of the struts is attached to a proximalcollar placed between a proximal stop element and a distal stop elementattached to the shaft member for preventing axial movement of theproximal collar along the shaft member.
 2. The embolic protection deviceof claim 1, wherein: the filtering assembly is rotatably mounted ontothe shaft member.
 3. The embolic protection device of claim 1, wherein:the set of struts and deployment member are made from a segment oftubing made from a self-expanding material which is laser cut to formthe individual struts and deployment member.
 4. The embolic protectiondevice of claim 3, wherein: the alternating peaks and valleys formingthe wave-like pattern of the deployment member are substantiallyV-shaped.
 5. The embolic protection device of claim 1, further includinga layer of polymeric material deposited on the proximal struts, thelayer of polymeric material having a coefficient of friction less thanthe coefficient of friction of the material forming the strut assembly.6. The embolic protection device of claim 5, wherein the polymericmaterial is selected from the group consisting of PTFE and polyimide. 7.The embolic protection device of claim 1, further including a layer ofheparin deposited on the filtering element.
 8. The embolic protectiondevice of claim 1, further including a layer of polymeric materialselectively deposited on the strut assembly.